x86/uprobes: Do not use prefixes.nbytes when looping over prefixes.bytes
commit5.4-rM2-2.2.x-imx-squashed4e9a5ae8df
upstream. Since insn.prefixes.nbytes can be bigger than the size of insn.prefixes.bytes[] when a prefix is repeated, the proper check must be insn.prefixes.bytes[i] != 0 and i < 4 instead of using insn.prefixes.nbytes. Introduce a for_each_insn_prefix() macro for this purpose. Debugged by Kees Cook <keescook@chromium.org>. [ bp: Massage commit message, sync with the respective header in tools/ and drop "we". ] Fixes:2b14449835
("uprobes, mm, x86: Add the ability to install and remove uprobes breakpoints") Reported-by: syzbot+9b64b619f10f19d19a7c@syzkaller.appspotmail.com Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/160697103739.3146288.7437620795200799020.stgit@devnote2 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -195,6 +195,21 @@ static inline int insn_offset_immediate(struct insn *insn)
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return insn_offset_displacement(insn) + insn->displacement.nbytes;
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return insn_offset_displacement(insn) + insn->displacement.nbytes;
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}
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}
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/**
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* for_each_insn_prefix() -- Iterate prefixes in the instruction
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* @insn: Pointer to struct insn.
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* @idx: Index storage.
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* @prefix: Prefix byte.
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*
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* Iterate prefix bytes of given @insn. Each prefix byte is stored in @prefix
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* and the index is stored in @idx (note that this @idx is just for a cursor,
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* do not change it.)
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* Since prefixes.nbytes can be bigger than 4 if some prefixes
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* are repeated, it cannot be used for looping over the prefixes.
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*/
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#define for_each_insn_prefix(insn, idx, prefix) \
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for (idx = 0; idx < ARRAY_SIZE(insn->prefixes.bytes) && (prefix = insn->prefixes.bytes[idx]) != 0; idx++)
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#define POP_SS_OPCODE 0x1f
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#define POP_SS_OPCODE 0x1f
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#define MOV_SREG_OPCODE 0x8e
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#define MOV_SREG_OPCODE 0x8e
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@ -255,12 +255,13 @@ static volatile u32 good_2byte_insns[256 / 32] = {
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static bool is_prefix_bad(struct insn *insn)
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static bool is_prefix_bad(struct insn *insn)
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{
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{
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insn_byte_t p;
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int i;
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int i;
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for (i = 0; i < insn->prefixes.nbytes; i++) {
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for_each_insn_prefix(insn, i, p) {
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insn_attr_t attr;
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insn_attr_t attr;
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attr = inat_get_opcode_attribute(insn->prefixes.bytes[i]);
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attr = inat_get_opcode_attribute(p);
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switch (attr) {
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switch (attr) {
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case INAT_MAKE_PREFIX(INAT_PFX_ES):
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case INAT_MAKE_PREFIX(INAT_PFX_ES):
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case INAT_MAKE_PREFIX(INAT_PFX_CS):
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case INAT_MAKE_PREFIX(INAT_PFX_CS):
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@ -715,6 +716,7 @@ static const struct uprobe_xol_ops push_xol_ops = {
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static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn)
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static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn)
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{
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{
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u8 opc1 = OPCODE1(insn);
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u8 opc1 = OPCODE1(insn);
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insn_byte_t p;
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int i;
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int i;
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switch (opc1) {
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switch (opc1) {
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@ -746,8 +748,8 @@ static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn)
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* Intel and AMD behavior differ in 64-bit mode: Intel ignores 66 prefix.
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* Intel and AMD behavior differ in 64-bit mode: Intel ignores 66 prefix.
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* No one uses these insns, reject any branch insns with such prefix.
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* No one uses these insns, reject any branch insns with such prefix.
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*/
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*/
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for (i = 0; i < insn->prefixes.nbytes; i++) {
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for_each_insn_prefix(insn, i, p) {
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if (insn->prefixes.bytes[i] == 0x66)
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if (p == 0x66)
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return -ENOTSUPP;
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return -ENOTSUPP;
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}
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}
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@ -195,6 +195,21 @@ static inline int insn_offset_immediate(struct insn *insn)
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return insn_offset_displacement(insn) + insn->displacement.nbytes;
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return insn_offset_displacement(insn) + insn->displacement.nbytes;
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}
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}
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/**
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* for_each_insn_prefix() -- Iterate prefixes in the instruction
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* @insn: Pointer to struct insn.
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* @idx: Index storage.
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* @prefix: Prefix byte.
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*
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* Iterate prefix bytes of given @insn. Each prefix byte is stored in @prefix
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* and the index is stored in @idx (note that this @idx is just for a cursor,
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* do not change it.)
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* Since prefixes.nbytes can be bigger than 4 if some prefixes
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* are repeated, it cannot be used for looping over the prefixes.
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*/
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#define for_each_insn_prefix(insn, idx, prefix) \
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for (idx = 0; idx < ARRAY_SIZE(insn->prefixes.bytes) && (prefix = insn->prefixes.bytes[idx]) != 0; idx++)
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#define POP_SS_OPCODE 0x1f
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#define POP_SS_OPCODE 0x1f
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#define MOV_SREG_OPCODE 0x8e
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#define MOV_SREG_OPCODE 0x8e
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