From: Zixuan Fu <r33s3n6@xxxxxxxxx> [ Upstream commit 0d4837fdb796f99369cf7691d33de1b856bcaf1f ] In our fault-injection testing, the variable "nblocks" in dbFree() can be zero when kmalloc_array() fails in dtSearch(). In this case, the variable "mp" in dbFree() would be NULL and then it is dereferenced in "write_metapage(mp)". The failure log is listed as follows: [ 13.824137] BUG: kernel NULL pointer dereference, address: 0000000000000020 ... [ 13.827416] RIP: 0010:dbFree+0x5f7/0x910 [jfs] [ 13.834341] Call Trace: [ 13.834540] <TASK> [ 13.834713] txFreeMap+0x7b4/0xb10 [jfs] [ 13.835038] txUpdateMap+0x311/0x650 [jfs] [ 13.835375] jfs_lazycommit+0x5f2/0xc70 [jfs] [ 13.835726] ? sched_dynamic_update+0x1b0/0x1b0 [ 13.836092] kthread+0x3c2/0x4a0 [ 13.836355] ? txLockFree+0x160/0x160 [jfs] [ 13.836763] ? kthread_unuse_mm+0x160/0x160 [ 13.837106] ret_from_fork+0x1f/0x30 [ 13.837402] </TASK> ... This patch adds a NULL check of "mp" before "write_metapage(mp)" is called. Reported-by: TOTE Robot <oslab@xxxxxxxxxxxxxxx> Signed-off-by: Zixuan Fu <r33s3n6@xxxxxxxxx> Signed-off-by: Dave Kleikamp <dave.kleikamp@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- fs/jfs/jfs_dmap.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c index f05805a10a50..1014f2a24697 100644 --- a/fs/jfs/jfs_dmap.c +++ b/fs/jfs/jfs_dmap.c @@ -398,7 +398,8 @@ int dbFree(struct inode *ip, s64 blkno, s64 nblocks) } /* write the last buffer. */ - write_metapage(mp); + if (mp) + write_metapage(mp); IREAD_UNLOCK(ipbmap); -- 2.35.1
