| Message ID | e84bc740-3502-4f16-982a-a40d5676615c@moroto.mountain (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] netfs, fscache: Prevent Oops in fscache_put_cache() | expand |
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);
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(-)