redonkable
/
alistair23-linux
1
0
Fork 0
Code Releases Activity

Quentin opened a can of worms by adding extable entry checking to modpost, 

but most architectures seem fixed now.  Thanks to all involved.
 
 Last minute rebase because I noticed a "[PATCH]" had snuck into a commit
 message somehow.
 
 Cheers,
 Rusty.
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v1
 
 iQIcBAABAgAGBQJVN1X3AAoJENkgDmzRrbjxmBEP/1Kv1wCrUGg07TfqNTJgr5Pe
 R81C+8P2wSEsA94lBhLNbn2DsN7uWsygcSXZMQ+5CrmbKAG45kRlMUzSlg6IdGXo
 usA9rOlH4hR+Dqn3zyx543xMJyp0a0LoSCLWGMmr/U71AXNp5kehvbIv64gJHrwg
 4CALI9qCwHH4FXF7WBYdLknlfpmD7KzCjIVckkfUfwf2A8mZXKdqBFQ+MPqbChEm
 vpFWkgp1oJgK4OcvvBeiNT2PwFZy1vmJtQWc2lieJ6HCjbqvwgM0g3EYTIQmccIm
 O40mEFMNkUuliMtrCZgOJBP2bmWy79JydiUq5Mu5Cb4bL6jGl2r6Z+w+iQ7Sggv9
 DTqTrk0/Cn02krJXDXAHVOXXgTqggf1xev6wr+3dbZn5sytQ8ddImuuVai8KALoC
 aEXAsnAK+3GnkAn9qqKVFhnrnCcI69I6srUAn5DKVWu36+Ye05FsZboIFYcxcK1F
 NZ+31xA17xA+yoo62ly/Auz7DXMa2QZfJcoQLMx2fMgL/+wMqzfGbcrZ5ZaVIj4w
 ePig1SbozAweAAfX7+W+QCQ3wqNN/nJgMO8vPldlcq7eaXH0/Dqu72cC2d82dK+H
 xl/1pEj83W0AkUkfNS8j3Z4zSzg31g8bK5SmPPRID00mx8roCfsP/Cfx5hRiO8U2
 ECtbKDxSyUWwF9vnOLVR
 =EYrW
 -----END PGP SIGNATURE-----

Merge tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux

Pull module updates from Rusty Russell:
 "Quentin opened a can of worms by adding extable entry checking to
  modpost, but most architectures seem fixed now.  Thanks to all
  involved.

  Last minute rebase because I noticed a "[PATCH]" had snuck into a
  commit message somehow"

* tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
  modpost: don't emit section mismatch warnings for compiler optimizations
  modpost: expand pattern matching to support substring matches
  modpost: do not try to match the SHT_NUL section.
  modpost: fix extable entry size calculation.
  modpost: fix inverted logic in is_extable_fault_address().
  modpost: handle -ffunction-sections
  modpost: Whitelist .text.fixup and .exception.text
  params: handle quotes properly for values not of form foo="bar".
  modpost: document the use of struct section_check.
  modpost: handle relocations mismatch in __ex_table.
  scripts: add check_extable.sh script.
  modpost: mismatch_handler: retrieve tosym information only when needed.
  modpost: factorize symbol pretty print in get_pretty_name().
  modpost: add handler function pointer to sectioncheck.
  modpost: add .sched.text and .kprobes.text to the TEXT_SECTIONS list.
  modpost: add strict white-listing when referencing sections.
  module: do not print allocation-fail warning on bogus user buffer size
  kernel/module.c: fix typos in message about unused symbols
hifive-unleashed-5.1
Linus Torvalds 2015-04-22 09:49:24 -07:00
parent f3ca10dde4 4a3893d069
commit 15ce2658dd
4 changed files with 440 additions and 60 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
kernel/module.c
View File

@ -387,9 +387,9 @@ static bool check_symbol(const struct symsearch *syms,
pr_warn("Symbol %s is marked as UNUSED, however this module is "
"using it.\n", fsa->name);
pr_warn("This symbol will go away in the future.\n");
pr_warn("Please evalute if this is the right api to use and if "
"it really is, submit a report the linux kernel "
"mailinglist together with submitting your code for "
pr_warn("Please evaluate if this is the right api to use and "
"if it really is, submit a report to the linux kernel "
"mailing list together with submitting your code for "
"inclusion.\n");
}
#endif
@ -2511,7 +2511,8 @@ static int copy_module_from_user(const void __user *umod, unsigned long len,
return err;
/* Suck in entire file: we'll want most of it. */
info->hdr = vmalloc(info->len);
info->hdr = __vmalloc(info->len,
GFP_KERNEL | __GFP_HIGHMEM | __GFP_NOWARN, PAGE_KERNEL);
if (!info->hdr)
return -ENOMEM;

4
kernel/params.c
View File

@ -173,9 +173,9 @@ static char *next_arg(char *args, char **param, char **val)
if (args[i-1] == '"')
args[i-1] = '\0';
}
if (quoted && args[i-1] == '"')
args[i-1] = '\0';
}
if (quoted && args[i-1] == '"')
args[i-1] = '\0';
if (args[i]) {
args[i] = '\0';

146
scripts/check_extable.sh 100755
View File

@ -0,0 +1,146 @@
#! /bin/bash
# (c) 2015, Quentin Casasnovas <quentin.casasnovas@oracle.com>
obj=$1
file ${obj} | grep -q ELF || (echo "${obj} is not and ELF file." 1>&2 ; exit 0)
# Bail out early if there isn't an __ex_table section in this object file.
objdump -hj __ex_table ${obj} 2> /dev/null > /dev/null
[ $? -ne 0 ] && exit 0
white_list=.text,.fixup
suspicious_relocs=$(objdump -rj __ex_table ${obj} | tail -n +6 |
grep -v $(eval echo -e{${white_list}}) | awk '{print $3}')
# No suspicious relocs in __ex_table, jobs a good'un
[ -z "${suspicious_relocs}" ] && exit 0
# After this point, something is seriously wrong since we just found out we
# have some relocations in __ex_table which point to sections which aren't
# white listed. If you're adding a new section in the Linux kernel, and
# you're expecting this section to contain code which can fault (i.e. the
# __ex_table relocation to your new section is expected), simply add your
# new section to the white_list variable above. If not, you're probably
# doing something wrong and the rest of this code is just trying to print
# you more information about it.
function find_section_offset_from_symbol()
{
eval $(objdump -t ${obj} | grep ${1} | sed 's/\([0-9a-f]\+\) .\{7\} \([^ \t]\+\).*/section="\2"; section_offset="0x\1" /')
# addr2line takes addresses in hexadecimal...
section_offset=$(printf "0x%016x" $(( ${section_offset} + $2 )) )
}
function find_symbol_and_offset_from_reloc()
{
# Extract symbol and offset from the objdump output
eval $(echo $reloc | sed 's/\([^+]\+\)+\?\(0x[0-9a-f]\+\)\?/symbol="\1"; symbol_offset="\2"/')
# When the relocation points to the begining of a symbol or section, it
# won't print the offset since it is zero.
if [ -z "${symbol_offset}" ]; then
symbol_offset=0x0
fi
}
function find_alt_replacement_target()
{
# The target of the .altinstr_replacement is the relocation just before
# the .altinstr_replacement one.
eval $(objdump -rj .altinstructions ${obj} | grep -B1 "${section}+${section_offset}" | head -n1 | awk '{print $3}' |
sed 's/\([^+]\+\)+\(0x[0-9a-f]\+\)/alt_target_section="\1"; alt_target_offset="\2"/')
}
function handle_alt_replacement_reloc()
{
# This will define alt_target_section and alt_target_section_offset
find_alt_replacement_target ${section} ${section_offset}
echo "Error: found a reference to .altinstr_replacement in __ex_table:"
addr2line -fip -j ${alt_target_section} -e ${obj} ${alt_target_offset} | awk '{print "\t" $0}'
error=true
}
function is_executable_section()
{
objdump -hwj ${section} ${obj} | grep -q CODE
return $?
}
function handle_suspicious_generic_reloc()
{
if is_executable_section ${section}; then
# We've got a relocation to a non white listed _executable_
# section, print a warning so the developper adds the section to
# the white list or fix his code. We try to pretty-print the file
# and line number where that relocation was added.
echo "Warning: found a reference to section \"${section}\" in __ex_table:"
addr2line -fip -j ${section} -e ${obj} ${section_offset} | awk '{print "\t" $0}'
else
# Something is definitively wrong here since we've got a relocation
# to a non-executable section, there's no way this would ever be
# running in the kernel.
echo "Error: found a reference to non-executable section \"${section}\" in __ex_table at offset ${section_offset}"
error=true
fi
}
function handle_suspicious_reloc()
{
case "${section}" in
".altinstr_replacement")
handle_alt_replacement_reloc ${section} ${section_offset}
;;
*)
handle_suspicious_generic_reloc ${section} ${section_offset}
;;
esac
}
function diagnose()
{
for reloc in ${suspicious_relocs}; do
# Let's find out where the target of the relocation in __ex_table
# is, this will define ${symbol} and ${symbol_offset}
find_symbol_and_offset_from_reloc ${reloc}
# When there's a global symbol at the place of the relocation,
# objdump will use it instead of giving us a section+offset, so
# let's find out which section is this symbol in and the total
# offset withing that section.
find_section_offset_from_symbol ${symbol} ${symbol_offset}
# In this case objdump was presenting us with a reloc to a symbol
# rather than a section. Now that we've got the actual section,
# we can skip it if it's in the white_list.
if [ -z "$( echo $section | grep -v $(eval echo -e{${white_list}}))" ]; then
continue;
fi
# Will either print a warning if the relocation happens to be in a
# section we do not know but has executable bit set, or error out.
handle_suspicious_reloc
done
}
function check_debug_info() {
objdump -hj .debug_info ${obj} 2> /dev/null > /dev/null ||
echo -e "${obj} does not contain debug information, the addr2line output will be limited.\n" \
"Recompile ${obj} with CONFIG_DEBUG_INFO to get a more useful output."
}
check_debug_info
diagnose
if [ "${error}" ]; then
exit 1
fi
exit 0

341
scripts/mod/modpost.c
View File

@ -776,6 +776,7 @@ static const char *sech_name(struct elf_info *elf, Elf_Shdr *sechdr)
* "foo" will match an exact string equal to "foo"
* "*foo" will match a string that ends with "foo"
* "foo*" will match a string that begins with "foo"
* "*foo*" will match a string that contains "foo"
*/
static int match(const char *sym, const char * const pat[])
{
@ -784,8 +785,17 @@ static int match(const char *sym, const char * const pat[])
p = *pat++;
const char *endp = p + strlen(p) - 1;
/* "*foo*" */
if (*p == '*' && *endp == '*') {
char *here, *bare = strndup(p + 1, strlen(p) - 2);
here = strstr(sym, bare);
free(bare);
if (here != NULL)
return 1;
}
/* "*foo" */
if (*p == '*') {
else if (*p == '*') {
if (strrcmp(sym, p + 1) == 0)
return 1;
}
@ -873,7 +883,10 @@ static void check_section(const char *modname, struct elf_info *elf,
#define ALL_EXIT_SECTIONS EXIT_SECTIONS, ALL_XXXEXIT_SECTIONS
#define DATA_SECTIONS ".data", ".data.rel"
#define TEXT_SECTIONS ".text", ".text.unlikely"
#define TEXT_SECTIONS ".text", ".text.unlikely", ".sched.text", \
".kprobes.text"
#define OTHER_TEXT_SECTIONS ".ref.text", ".head.text", ".spinlock.text", \
".fixup", ".entry.text", ".exception.text", ".text.*"
#define INIT_SECTIONS ".init.*"
#define MEM_INIT_SECTIONS ".meminit.*"
@ -881,6 +894,9 @@ static void check_section(const char *modname, struct elf_info *elf,
#define EXIT_SECTIONS ".exit.*"
#define MEM_EXIT_SECTIONS ".memexit.*"
#define ALL_TEXT_SECTIONS ALL_INIT_TEXT_SECTIONS, ALL_EXIT_TEXT_SECTIONS, \
TEXT_SECTIONS, OTHER_TEXT_SECTIONS
/* init data sections */
static const char *const init_data_sections[] =
{ ALL_INIT_DATA_SECTIONS, NULL };
@ -892,6 +908,9 @@ static const char *const init_sections[] = { ALL_INIT_SECTIONS, NULL };
static const char *const init_exit_sections[] =
{ALL_INIT_SECTIONS, ALL_EXIT_SECTIONS, NULL };
/* all text sections */
static const char *const text_sections[] = { ALL_TEXT_SECTIONS, NULL };
/* data section */
static const char *const data_sections[] = { DATA_SECTIONS, NULL };
@ -910,6 +929,7 @@ static const char *const data_sections[] = { DATA_SECTIONS, NULL };
static const char *const head_sections[] = { ".head.text*", NULL };
static const char *const linker_symbols[] =
{ "__init_begin", "_sinittext", "_einittext", NULL };
static const char *const optim_symbols[] = { "*.constprop.*", NULL };
enum mismatch {
TEXT_TO_ANY_INIT,
@ -921,34 +941,65 @@ enum mismatch {
ANY_INIT_TO_ANY_EXIT,
ANY_EXIT_TO_ANY_INIT,
EXPORT_TO_INIT_EXIT,
EXTABLE_TO_NON_TEXT,
};
/**
* Describe how to match sections on different criterias:
*
* @fromsec: Array of sections to be matched.
*
* @bad_tosec: Relocations applied to a section in @fromsec to a section in
* this array is forbidden (black-list). Can be empty.
*
* @good_tosec: Relocations applied to a section in @fromsec must be
* targetting sections in this array (white-list). Can be empty.
*
* @mismatch: Type of mismatch.
*
* @symbol_white_list: Do not match a relocation to a symbol in this list
* even if it is targetting a section in @bad_to_sec.
*
* @handler: Specific handler to call when a match is found. If NULL,
* default_mismatch_handler() will be called.
*
*/
struct sectioncheck {
const char *fromsec[20];
const char *tosec[20];
const char *bad_tosec[20];
const char *good_tosec[20];
enum mismatch mismatch;
const char *symbol_white_list[20];
void (*handler)(const char *modname, struct elf_info *elf,
const struct sectioncheck* const mismatch,
Elf_Rela *r, Elf_Sym *sym, const char *fromsec);
};
static void extable_mismatch_handler(const char *modname, struct elf_info *elf,
const struct sectioncheck* const mismatch,
Elf_Rela *r, Elf_Sym *sym,
const char *fromsec);
static const struct sectioncheck sectioncheck[] = {
/* Do not reference init/exit code/data from
* normal code and data
*/
{
.fromsec = { TEXT_SECTIONS, NULL },
.tosec = { ALL_INIT_SECTIONS, NULL },
.bad_tosec = { ALL_INIT_SECTIONS, NULL },
.mismatch = TEXT_TO_ANY_INIT,
.symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
},
{
.fromsec = { DATA_SECTIONS, NULL },
.tosec = { ALL_XXXINIT_SECTIONS, NULL },
.bad_tosec = { ALL_XXXINIT_SECTIONS, NULL },
.mismatch = DATA_TO_ANY_INIT,
.symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
},
{
.fromsec = { DATA_SECTIONS, NULL },
.tosec = { INIT_SECTIONS, NULL },
.bad_tosec = { INIT_SECTIONS, NULL },
.mismatch = DATA_TO_ANY_INIT,
.symbol_white_list = {
"*_template", "*_timer", "*_sht", "*_ops",
@ -957,56 +1008,66 @@ static const struct sectioncheck sectioncheck[] = {
},
{
.fromsec = { TEXT_SECTIONS, NULL },
.tosec = { ALL_EXIT_SECTIONS, NULL },
.bad_tosec = { ALL_EXIT_SECTIONS, NULL },
.mismatch = TEXT_TO_ANY_EXIT,
.symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
},
{
.fromsec = { DATA_SECTIONS, NULL },
.tosec = { ALL_EXIT_SECTIONS, NULL },
.bad_tosec = { ALL_EXIT_SECTIONS, NULL },
.mismatch = DATA_TO_ANY_EXIT,
.symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
},
/* Do not reference init code/data from meminit code/data */
{
.fromsec = { ALL_XXXINIT_SECTIONS, NULL },
.tosec = { INIT_SECTIONS, NULL },
.bad_tosec = { INIT_SECTIONS, NULL },
.mismatch = XXXINIT_TO_SOME_INIT,
.symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
},
/* Do not reference exit code/data from memexit code/data */
{
.fromsec = { ALL_XXXEXIT_SECTIONS, NULL },
.tosec = { EXIT_SECTIONS, NULL },
.bad_tosec = { EXIT_SECTIONS, NULL },
.mismatch = XXXEXIT_TO_SOME_EXIT,
.symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
},
/* Do not use exit code/data from init code */
{
.fromsec = { ALL_INIT_SECTIONS, NULL },
.tosec = { ALL_EXIT_SECTIONS, NULL },
.bad_tosec = { ALL_EXIT_SECTIONS, NULL },
.mismatch = ANY_INIT_TO_ANY_EXIT,
.symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
},
/* Do not use init code/data from exit code */
{
.fromsec = { ALL_EXIT_SECTIONS, NULL },
.tosec = { ALL_INIT_SECTIONS, NULL },
.bad_tosec = { ALL_INIT_SECTIONS, NULL },
.mismatch = ANY_EXIT_TO_ANY_INIT,
.symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
},
{
.fromsec = { ALL_PCI_INIT_SECTIONS, NULL },
.tosec = { INIT_SECTIONS, NULL },
.bad_tosec = { INIT_SECTIONS, NULL },
.mismatch = ANY_INIT_TO_ANY_EXIT,
.symbol_white_list = { NULL },
},
/* Do not export init/exit functions or data */
{
.fromsec = { "__ksymtab*", NULL },
.tosec = { INIT_SECTIONS, EXIT_SECTIONS, NULL },
.bad_tosec = { INIT_SECTIONS, EXIT_SECTIONS, NULL },
.mismatch = EXPORT_TO_INIT_EXIT,
.symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
},
{
.fromsec = { "__ex_table", NULL },
/* If you're adding any new black-listed sections in here, consider
* adding a special 'printer' for them in scripts/check_extable.
*/
.bad_tosec = { ".altinstr_replacement", NULL },
.good_tosec = {ALL_TEXT_SECTIONS , NULL},
.mismatch = EXTABLE_TO_NON_TEXT,
.handler = extable_mismatch_handler,
}
};
@ -1017,10 +1078,22 @@ static const struct sectioncheck *section_mismatch(
int elems = sizeof(sectioncheck) / sizeof(struct sectioncheck);
const struct sectioncheck *check = &sectioncheck[0];
/*
* The target section could be the SHT_NUL section when we're
* handling relocations to un-resolved symbols, trying to match it
* doesn't make much sense and causes build failures on parisc and
* mn10300 architectures.
*/
if (*tosec == '\0')
return NULL;
for (i = 0; i < elems; i++) {
if (match(fromsec, check->fromsec) &&
match(tosec, check->tosec))
return check;
if (match(fromsec, check->fromsec)) {
if (check->bad_tosec[0] && match(tosec, check->bad_tosec))
return check;
if (check->good_tosec[0] && !match(tosec, check->good_tosec))
return check;
}
check++;
}
return NULL;
@ -1067,6 +1140,17 @@ static const struct sectioncheck *section_mismatch(
* This pattern is identified by
* refsymname = __init_begin, _sinittext, _einittext
*
* Pattern 5:
* GCC may optimize static inlines when fed constant arg(s) resulting
* in functions like cpumask_empty() -- generating an associated symbol
* cpumask_empty.constprop.3 that appears in the audit. If the const that
* is passed in comes from __init, like say nmi_ipi_mask, we get a
* meaningless section warning. May need to add isra symbols too...
* This pattern is identified by
* tosec = init section
* fromsec = text section
* refsymname = *.constprop.*
*
**/
static int secref_whitelist(const struct sectioncheck *mismatch,
const char *fromsec, const char *fromsym,
@ -1099,6 +1183,12 @@ static int secref_whitelist(const struct sectioncheck *mismatch,
if (match(tosym, linker_symbols))
return 0;
/* Check for pattern 5 */
if (match(fromsec, text_sections) &&
match(tosec, init_sections) &&
match(fromsym, optim_symbols))
return 0;
return 1;
}
@ -1261,6 +1351,15 @@ static void print_section_list(const char * const list[20])
fprintf(stderr, "\n");
}
static inline void get_pretty_name(int is_func, const char** name, const char** name_p)
{
switch (is_func) {
case 0: *name = "variable"; *name_p = ""; break;
case 1: *name = "function"; *name_p = "()"; break;
default: *name = "(unknown reference)"; *name_p = ""; break;
}
}
/*
* Print a warning about a section mismatch.
* Try to find symbols near it so user can find it.
@ -1280,21 +1379,13 @@ static void report_sec_mismatch(const char *modname,
char *prl_from;
char *prl_to;
switch (from_is_func) {
case 0: from = "variable"; from_p = ""; break;
case 1: from = "function"; from_p = "()"; break;
default: from = "(unknown reference)"; from_p = ""; break;
}
switch (to_is_func) {
case 0: to = "variable"; to_p = ""; break;
case 1: to = "function"; to_p = "()"; break;
default: to = "(unknown reference)"; to_p = ""; break;
}
sec_mismatch_count++;
if (!sec_mismatch_verbose)
return;
get_pretty_name(from_is_func, &from, &from_p);
get_pretty_name(to_is_func, &to, &to_p);
warn("%s(%s+0x%llx): Section mismatch in reference from the %s %s%s "
"to the %s %s:%s%s\n",
modname, fromsec, fromaddr, from, fromsym, from_p, to, tosec,
@ -1408,41 +1499,179 @@ static void report_sec_mismatch(const char *modname,
tosym, prl_to, prl_to, tosym);
free(prl_to);
break;
case EXTABLE_TO_NON_TEXT:
fatal("There's a special handler for this mismatch type, "
"we should never get here.");
break;
}
fprintf(stderr, "\n");
}
static void default_mismatch_handler(const char *modname, struct elf_info *elf,
const struct sectioncheck* const mismatch,
Elf_Rela *r, Elf_Sym *sym, const char *fromsec)
{
const char *tosec;
Elf_Sym *to;
Elf_Sym *from;
const char *tosym;
const char *fromsym;
from = find_elf_symbol2(elf, r->r_offset, fromsec);
fromsym = sym_name(elf, from);
if (!strncmp(fromsym, "reference___initcall",
sizeof("reference___initcall")-1))
return;
tosec = sec_name(elf, get_secindex(elf, sym));
to = find_elf_symbol(elf, r->r_addend, sym);
tosym = sym_name(elf, to);
/* check whitelist - we may ignore it */
if (secref_whitelist(mismatch,
fromsec, fromsym, tosec, tosym)) {
report_sec_mismatch(modname, mismatch,
fromsec, r->r_offset, fromsym,
is_function(from), tosec, tosym,
is_function(to));
}
}
static int is_executable_section(struct elf_info* elf, unsigned int section_index)
{
if (section_index > elf->num_sections)
fatal("section_index is outside elf->num_sections!\n");
return ((elf->sechdrs[section_index].sh_flags & SHF_EXECINSTR) == SHF_EXECINSTR);
}
/*
* We rely on a gross hack in section_rel[a]() calling find_extable_entry_size()
* to know the sizeof(struct exception_table_entry) for the target architecture.
*/
static unsigned int extable_entry_size = 0;
static void find_extable_entry_size(const char* const sec, const Elf_Rela* r)
{
/*
* If we're currently checking the second relocation within __ex_table,
* that relocation offset tells us the offsetof(struct
* exception_table_entry, fixup) which is equal to sizeof(struct
* exception_table_entry) divided by two. We use that to our advantage
* since there's no portable way to get that size as every architecture
* seems to go with different sized types. Not pretty but better than
* hard-coding the size for every architecture..
*/
if (!extable_entry_size)
extable_entry_size = r->r_offset * 2;
}
static inline bool is_extable_fault_address(Elf_Rela *r)
{
/*
* extable_entry_size is only discovered after we've handled the
* _second_ relocation in __ex_table, so only abort when we're not
* handling the first reloc and extable_entry_size is zero.
*/
if (r->r_offset && extable_entry_size == 0)
fatal("extable_entry size hasn't been discovered!\n");
return ((r->r_offset == 0) ||
(r->r_offset % extable_entry_size == 0));
}
#define is_second_extable_reloc(Start, Cur, Sec) \
(((Cur) == (Start) + 1) && (strcmp("__ex_table", (Sec)) == 0))
static void report_extable_warnings(const char* modname, struct elf_info* elf,
const struct sectioncheck* const mismatch,
Elf_Rela* r, Elf_Sym* sym,
const char* fromsec, const char* tosec)
{
Elf_Sym* fromsym = find_elf_symbol2(elf, r->r_offset, fromsec);
const char* fromsym_name = sym_name(elf, fromsym);
Elf_Sym* tosym = find_elf_symbol(elf, r->r_addend, sym);
const char* tosym_name = sym_name(elf, tosym);
const char* from_pretty_name;
const char* from_pretty_name_p;
const char* to_pretty_name;
const char* to_pretty_name_p;
get_pretty_name(is_function(fromsym),
&from_pretty_name, &from_pretty_name_p);
get_pretty_name(is_function(tosym),
&to_pretty_name, &to_pretty_name_p);
warn("%s(%s+0x%lx): Section mismatch in reference"
" from the %s %s%s to the %s %s:%s%s\n",
modname, fromsec, (long)r->r_offset, from_pretty_name,
fromsym_name, from_pretty_name_p,
to_pretty_name, tosec, tosym_name, to_pretty_name_p);
if (!match(tosec, mismatch->bad_tosec) &&
is_executable_section(elf, get_secindex(elf, sym)))
fprintf(stderr,
"The relocation at %s+0x%lx references\n"
"section \"%s\" which is not in the list of\n"
"authorized sections. If you're adding a new section\n"
"and/or if this reference is valid, add \"%s\" to the\n"
"list of authorized sections to jump to on fault.\n"
"This can be achieved by adding \"%s\" to \n"
"OTHER_TEXT_SECTIONS in scripts/mod/modpost.c.\n",
fromsec, (long)r->r_offset, tosec, tosec, tosec);
}
static void extable_mismatch_handler(const char* modname, struct elf_info *elf,
const struct sectioncheck* const mismatch,
Elf_Rela* r, Elf_Sym* sym,
const char *fromsec)
{
const char* tosec = sec_name(elf, get_secindex(elf, sym));
sec_mismatch_count++;
if (sec_mismatch_verbose)
report_extable_warnings(modname, elf, mismatch, r, sym,
fromsec, tosec);
if (match(tosec, mismatch->bad_tosec))
fatal("The relocation at %s+0x%lx references\n"
"section \"%s\" which is black-listed.\n"
"Something is seriously wrong and should be fixed.\n"
"You might get more information about where this is\n"
"coming from by using scripts/check_extable.sh %s\n",
fromsec, (long)r->r_offset, tosec, modname);
else if (!is_executable_section(elf, get_secindex(elf, sym))) {
if (is_extable_fault_address(r))
fatal("The relocation at %s+0x%lx references\n"
"section \"%s\" which is not executable, IOW\n"
"it is not possible for the kernel to fault\n"
"at that address. Something is seriously wrong\n"
"and should be fixed.\n",
fromsec, (long)r->r_offset, tosec);
else
fatal("The relocation at %s+0x%lx references\n"
"section \"%s\" which is not executable, IOW\n"
"the kernel will fault if it ever tries to\n"
"jump to it. Something is seriously wrong\n"
"and should be fixed.\n",
fromsec, (long)r->r_offset, tosec);
}
}
static void check_section_mismatch(const char *modname, struct elf_info *elf,
Elf_Rela *r, Elf_Sym *sym, const char *fromsec)
{
const char *tosec;
const struct sectioncheck *mismatch;
const char *tosec = sec_name(elf, get_secindex(elf, sym));;
const struct sectioncheck *mismatch = section_mismatch(fromsec, tosec);
tosec = sec_name(elf, get_secindex(elf, sym));
mismatch = section_mismatch(fromsec, tosec);
if (mismatch) {
Elf_Sym *to;
Elf_Sym *from;
const char *tosym;
const char *fromsym;
from = find_elf_symbol2(elf, r->r_offset, fromsec);
fromsym = sym_name(elf, from);
to = find_elf_symbol(elf, r->r_addend, sym);
tosym = sym_name(elf, to);
if (!strncmp(fromsym, "reference___initcall",
sizeof("reference___initcall")-1))
return;
/* check whitelist - we may ignore it */
if (secref_whitelist(mismatch,
fromsec, fromsym, tosec, tosym)) {
report_sec_mismatch(modname, mismatch,
fromsec, r->r_offset, fromsym,
is_function(from), tosec, tosym,
is_function(to));
}
if (mismatch->handler)
mismatch->handler(modname, elf, mismatch,
r, sym, fromsec);
else
default_mismatch_handler(modname, elf, mismatch,
r, sym, fromsec);
}
}
@ -1582,6 +1811,8 @@ static void section_rela(const char *modname, struct elf_info *elf,
/* Skip special sections */
if (is_shndx_special(sym->st_shndx))
continue;
if (is_second_extable_reloc(start, rela, fromsec))
find_extable_entry_size(fromsec, &r);
check_section_mismatch(modname, elf, &r, sym, fromsec);
}
}
@ -1640,6 +1871,8 @@ static void section_rel(const char *modname, struct elf_info *elf,
/* Skip special sections */
if (is_shndx_special(sym->st_shndx))
continue;
if (is_second_extable_reloc(start, rel, fromsec))
find_extable_entry_size(fromsec, &r);
check_section_mismatch(modname, elf, &r, sym, fromsec);
}
}