github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-05-12 16:18:45 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity

fs/buffer: add alert in try_to_free_buffers() for folios without buffers

Browse Source 
try_to_free_buffers() can be called on folios with no buffers attached
when filemap_release_folio() is invoked on a folio belonging to a mapping
with AS_RELEASE_ALWAYS set but no release_folio operation defined.

In such cases, folio_needs_release() returns true because of the
AS_RELEASE_ALWAYS flag, but the folio has no private buffer data. This
causes try_to_free_buffers() to call drop_buffers() on a folio with no
buffers, leading to a null pointer dereference.

Adding a check in try_to_free_buffers() to return early if the folio has no
buffers attached, with WARN_ON_ONCE() to alert about the misconfiguration.
This provides defensive hardening.

Signed-off-by: Deepakkumar Karn <dkarn@redhat.com>
Link: https://patch.msgid.link/20251211131211.308021-1-dkarn@redhat.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Deepakkumar Karn 2025-12-11 18:42:11 +05:30 committed by Christian Brauner
parent 961b2ad1b4
commit b68f91ef3b
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
1 changed files with 4 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
fs/buffer.c
View File

@ -2948,6 +2948,10 @@ bool try_to_free_buffers(struct folio *folio)
if (folio_test_writeback(folio))
return false;
/* Misconfigured folio check */
if (WARN_ON_ONCE(!folio_buffers(folio)))
return true;
if (mapping == NULL) { /* can this still happen? */
ret = drop_buffers(folio, &buffers_to_free);
goto out;