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| author | Rand Deeb <rand.sec96@gmail.com> | 2025-02-20 12:52:31 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-04-20 11:15:18 +0300 |
| commit | c802a6a4009f585111f903e810b3be9c6d0da329 (patch) | |
| tree | b427ba79718e26eeb09684c0263229a41281b718 | |
| parent | 319877db0aa9624b4b2b3b902f56858c8a0f4491 (diff) | |
| download | linux-c802a6a4009f585111f903e810b3be9c6d0da329.tar.xz | |
fs/jfs: Prevent integer overflow in AG size calculation
[ Upstream commit 7fcbf789629cdb9fbf4e2172ce31136cfed11e5e ]
The JFS filesystem calculates allocation group (AG) size using 1 <<
l2agsize in dbExtendFS(). When l2agsize exceeds 31 (possible with >2TB
aggregates on 32-bit systems), this 32-bit shift operation causes undefined
behavior and improper AG sizing.
On 32-bit architectures:
- Left-shifting 1 by 32+ bits results in 0 due to integer overflow
- This creates invalid AG sizes (0 or garbage values) in
sbi->bmap->db_agsize
- Subsequent block allocations would reference invalid AG structures
- Could lead to:
- Filesystem corruption during extend operations
- Kernel crashes due to invalid memory accesses
- Security vulnerabilities via malformed on-disk structures
Fix by casting to s64 before shifting:
bmp->db_agsize = (s64)1 << l2agsize;
This ensures 64-bit arithmetic even on 32-bit architectures. The cast
matches the data type of db_agsize (s64) and follows similar patterns in
JFS block calculation code.
Found by Linux Verification Center (linuxtesting.org) with SVACE.
Signed-off-by: Rand Deeb <rand.sec96@gmail.com>
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | fs/jfs/jfs_dmap.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c index f89f07c9580e..9ac1fc2ed05b 100644 --- a/fs/jfs/jfs_dmap.c +++ b/fs/jfs/jfs_dmap.c @@ -3403,7 +3403,7 @@ int dbExtendFS(struct inode *ipbmap, s64 blkno, s64 nblocks) oldl2agsize = bmp->db_agl2size; bmp->db_agl2size = l2agsize; - bmp->db_agsize = 1 << l2agsize; + bmp->db_agsize = (s64)1 << l2agsize; /* compute new number of AG */ agno = bmp->db_numag; |