* [PATCH v2] netfs, fscache: Prevent Oops in fscache_put_cache()
@ 2024-01-12 6:59 Dan Carpenter
0 siblings, 0 replies; only message in thread
From: Dan Carpenter @ 2024-01-12 6:59 UTC (permalink / raw)
To: David Howells
Cc: Jeff Layton, linux-cachefs, linux-fsdevel, linux-kernel, kernel-janitors
This function dereferences "cache" and then checks if it's
IS_ERR_OR_NULL(). Check first, then dereference.
Fixes: 9549332df4ed ("fscache: Implement cache registration")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
---
v2: My first version introduced a race and a possible use after free.
fs/netfs/fscache_cache.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/netfs/fscache_cache.c b/fs/netfs/fscache_cache.c
index d645f8b302a2..9397ed39b0b4 100644
--- a/fs/netfs/fscache_cache.c
+++ b/fs/netfs/fscache_cache.c
@@ -179,13 +179,14 @@ EXPORT_SYMBOL(fscache_acquire_cache);
void fscache_put_cache(struct fscache_cache *cache,
enum fscache_cache_trace where)
{
- unsigned int debug_id = cache->debug_id;
+ unsigned int debug_id;
bool zero;
int ref;
if (IS_ERR_OR_NULL(cache))
return;
+ debug_id = cache->debug_id;
zero = __refcount_dec_and_test(&cache->ref, &ref);
trace_fscache_cache(debug_id, ref - 1, where);
--
2.43.0
^ permalink raw reply related [flat|nested] only message in thread
only message in thread, other threads:[~2024-01-12 6:59 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2024-01-12 6:59 [PATCH v2] netfs, fscache: Prevent Oops in fscache_put_cache() Dan Carpenter
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).