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dyndbg: fix a BUG_ON in ddebug_describe_flags 

[ Upstream commit f678ce8cc3 ]

ddebug_describe_flags() currently fills a caller provided string buffer,
after testing its size (also passed) in a BUG_ON.  Fix this by
replacing them with a known-big-enough string buffer wrapped in a
struct, and passing that instead.

Also simplify ddebug_describe_flags() flags parameter from a struct to
a member in that struct, and hoist the member deref up to the caller.
This makes the function reusable (soon) where flags are unpacked.

Acked-by: <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200719231058.1586423-8-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
5.4-rM2-2.2.x-imx-squashed
Jim Cromie 2020-07-19 17:10:47 -06:00 committed by Greg Kroah-Hartman
parent 8fb05790b5
commit db9b14ae4b
1 changed files with 11 additions and 12 deletions
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23
lib/dynamic_debug.c
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@ -87,22 +87,22 @@ static struct { unsigned flag:8; char opt_char; } opt_array[] = {
{ _DPRINTK_FLAGS_NONE, '_' }, { _DPRINTK_FLAGS_NONE, '_' },
}; };
struct flagsbuf { char buf[ARRAY_SIZE(opt_array)+1]; };
/* format a string into buf[] which describes the _ddebug's flags */ /* format a string into buf[] which describes the _ddebug's flags */
static char *ddebug_describe_flags(struct _ddebug *dp, char *buf, static char *ddebug_describe_flags(unsigned int flags, struct flagsbuf *fb)
size_t maxlen)
{ {
char *p = buf; char *p = fb->buf;
int i; int i;
BUG_ON(maxlen < 6);
for (i = 0; i < ARRAY_SIZE(opt_array); ++i) for (i = 0; i < ARRAY_SIZE(opt_array); ++i)
if (dp->flags & opt_array[i].flag) if (flags & opt_array[i].flag)
*p++ = opt_array[i].opt_char; *p++ = opt_array[i].opt_char;
if (p == buf) if (p == fb->buf)
*p++ = '_'; *p++ = '_';
*p = '\0'; *p = '\0';
return buf; return fb->buf;
} }
#define vpr_info(fmt, ...) \ #define vpr_info(fmt, ...) \
@ -144,7 +144,7 @@ static int ddebug_change(const struct ddebug_query *query,
struct ddebug_table *dt; struct ddebug_table *dt;
unsigned int newflags; unsigned int newflags;
unsigned int nfound = 0; unsigned int nfound = 0;
char flagbuf[10]; struct flagsbuf fbuf;
/* search for matching ddebugs */ /* search for matching ddebugs */
mutex_lock(&ddebug_lock); mutex_lock(&ddebug_lock);
@ -201,8 +201,7 @@ static int ddebug_change(const struct ddebug_query *query,
vpr_info("changed %s:%d [%s]%s =%s\n", vpr_info("changed %s:%d [%s]%s =%s\n",
trim_prefix(dp->filename), dp->lineno, trim_prefix(dp->filename), dp->lineno,
dt->mod_name, dp->function, dt->mod_name, dp->function,
ddebug_describe_flags(dp, flagbuf, ddebug_describe_flags(dp->flags, &fbuf));
sizeof(flagbuf)));
} }
} }
mutex_unlock(&ddebug_lock); mutex_unlock(&ddebug_lock);
@ -816,7 +815,7 @@ static int ddebug_proc_show(struct seq_file *m, void *p)
{ {
struct ddebug_iter *iter = m->private; struct ddebug_iter *iter = m->private;
struct _ddebug *dp = p; struct _ddebug *dp = p;
char flagsbuf[10]; struct flagsbuf flags;
vpr_info("called m=%p p=%p\n", m, p); vpr_info("called m=%p p=%p\n", m, p);
@ -829,7 +828,7 @@ static int ddebug_proc_show(struct seq_file *m, void *p)
seq_printf(m, "%s:%u [%s]%s =%s \"", seq_printf(m, "%s:%u [%s]%s =%s \"",
trim_prefix(dp->filename), dp->lineno, trim_prefix(dp->filename), dp->lineno,
iter->table->mod_name, dp->function, iter->table->mod_name, dp->function,
ddebug_describe_flags(dp, flagsbuf, sizeof(flagsbuf))); ddebug_describe_flags(dp->flags, &flags));
seq_escape(m, dp->format, "\t\r\n\""); seq_escape(m, dp->format, "\t\r\n\"");
seq_puts(m, "\"\n"); seq_puts(m, "\"\n");