On Mon 2020-08-17 17:16:22, Greg Kroah-Hartman wrote:
From: Jim Cromie jim.cromie@gmail.com
[ Upstream commit f678ce8cc3cb2ad29df75d8824c74f36398ba871 ]
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.
Original code was correct, passing explicit size, this passes strange structure. BUG_ON can never trigger in the origianl code, so this is not a bugfix.
Best regards, Pavel
+++ b/lib/dynamic_debug.c @@ -85,22 +85,22 @@ static struct { unsigned flag:8; char opt_char; } opt_array[] = { { _DPRINTK_FLAGS_NONE, '_' }, }; +struct flagsbuf { char buf[ARRAY_SIZE(opt_array)+1]; };
/* format a string into buf[] which describes the _ddebug's flags */ -static char *ddebug_describe_flags(struct _ddebug *dp, char *buf,
size_t maxlen)+static char *ddebug_describe_flags(unsigned int flags, struct flagsbuf *fb) {
- char *p = buf;
- char *p = fb->buf; int i;
- BUG_ON(maxlen < 6); 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;
- if (p == buf)
- if (p == fb->buf) *p++ = '_'; *p = '\0';
- return buf;
- return fb->buf;
} #define vpr_info(fmt, ...) \ @@ -142,7 +142,7 @@ static int ddebug_change(const struct ddebug_query *query, struct ddebug_table *dt; unsigned int newflags; unsigned int nfound = 0;
- char flagbuf[10];
- struct flagsbuf fbuf;
/* search for matching ddebugs */ mutex_lock(&ddebug_lock); @@ -199,8 +199,7 @@ static int ddebug_change(const struct ddebug_query *query, vpr_info("changed %s:%d [%s]%s =%s\n", trim_prefix(dp->filename), dp->lineno, dt->mod_name, dp->function,
ddebug_describe_flags(dp, flagbuf,sizeof(flagbuf)));
ddebug_describe_flags(dp->flags, &fbuf));@@ -779,7 +778,7 @@ static int ddebug_proc_show(struct seq_file *m, void *p) { struct ddebug_iter *iter = m->private; struct _ddebug *dp = p;
- char flagsbuf[10];
- struct flagsbuf flags;
vpr_info("called m=%p p=%p\n", m, p); @@ -792,7 +791,7 @@ static int ddebug_proc_show(struct seq_file *m, void *p) seq_printf(m, "%s:%u [%s]%s =%s "", trim_prefix(dp->filename), dp->lineno, iter->table->mod_name, dp->function,
ddebug_describe_flags(dp, flagsbuf, sizeof(flagsbuf)));
ddebug_describe_flags(dp->flags, &flags));