diff options
| author | Jack Wang <jinpu.wang@ionos.com> | 2026-01-20 11:24:56 +0100 |
|---|---|---|
| committer | Sasha Levin <sashal@kernel.org> | 2026-03-04 07:20:19 -0500 |
| commit | 140cc839fbeb1ddb33a8da8811b716d88d3905b7 (patch) | |
| tree | be612cd9ef35b69581484eeb948b3559b887c028 | |
| parent | 2b1b1734beeabd107317b00762eab5b6654c3bf4 (diff) | |
md/bitmap: fix GPF in write_page caused by resize race
[ Upstream commit 46ef85f854dfa9d5226b3c1c46493d79556c9589 ]
A General Protection Fault occurs in write_page() during array resize:
RIP: 0010:write_page+0x22b/0x3c0 [md_mod]
This is a use-after-free race between bitmap_daemon_work() and
__bitmap_resize(). The daemon iterates over `bitmap->storage.filemap`
without locking, while the resize path frees that storage via
md_bitmap_file_unmap(). `quiesce()` does not stop the md thread,
allowing concurrent access to freed pages.
Fix by holding `mddev->bitmap_info.mutex` during the bitmap update.
Link: https://lore.kernel.org/linux-raid/20260120102456.25169-1-jinpu.wang@ionos.com
Closes: https://lore.kernel.org/linux-raid/CAMGffE=Mbfp=7xD_hYxXk1PAaCZNSEAVeQGKGy7YF9f2S4=NEA@mail.gmail.com/T/#u
Cc: stable@vger.kernel.org
Fixes: d60b479d177a ("md/bitmap: add bitmap_resize function to allow bitmap resizing.")
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Yu Kuai <yukuai@fnnas.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | drivers/md/md-bitmap.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c index f2ba541ed89d..61ac67200c8f 100644 --- a/drivers/md/md-bitmap.c +++ b/drivers/md/md-bitmap.c @@ -2143,6 +2143,7 @@ int md_bitmap_resize(struct bitmap *bitmap, sector_t blocks, memcpy(page_address(store.sb_page), page_address(bitmap->storage.sb_page), sizeof(bitmap_super_t)); + mutex_lock(&bitmap->mddev->bitmap_info.mutex); spin_lock_irq(&bitmap->counts.lock); md_bitmap_file_unmap(&bitmap->storage); bitmap->storage = store; @@ -2250,7 +2251,7 @@ int md_bitmap_resize(struct bitmap *bitmap, sector_t blocks, set_page_attr(bitmap, i, BITMAP_PAGE_DIRTY); } spin_unlock_irq(&bitmap->counts.lock); - + mutex_unlock(&bitmap->mddev->bitmap_info.mutex); if (!init) { md_bitmap_unplug(bitmap); bitmap->mddev->pers->quiesce(bitmap->mddev, 0); |