netfs, fscache: Prevent Oops in fscache_put_cache()

This function dereferences "cache" and then checks if it's
IS_ERR_OR_NULL().  Check first, then dereference.

Fixes: 9549332df4 ("fscache: Implement cache registration")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/e84bc740-3502-4f16-982a-a40d5676615c@moroto.mountain/ # v2
This commit is contained in:
Dan Carpenter 2024-01-12 09:59:41 +03:00 committed by David Howells
parent c40497d823
commit 3be0b3ed1d

View File

@ -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);