5.4-stable review patch. If anyone has any objections, please let me know.
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From: Li Lingfeng lilingfeng3@huawei.com
[ Upstream commit c457dc1ec770a22636b473ce5d35614adfe97636 ]
When memory is insufficient, the allocation of nfs_lock_context in nfs_get_lock_context() fails and returns -ENOMEM. If we mistakenly treat an nfs4_unlockdata structure (whose l_ctx member has been set to -ENOMEM) as valid and proceed to execute rpc_run_task(), this will trigger a NULL pointer dereference in nfs4_locku_prepare. For example:
BUG: kernel NULL pointer dereference, address: 000000000000000c PGD 0 P4D 0 Oops: Oops: 0000 [#1] SMP PTI CPU: 15 UID: 0 PID: 12 Comm: kworker/u64:0 Not tainted 6.15.0-rc2-dirty #60 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-2.fc40 Workqueue: rpciod rpc_async_schedule RIP: 0010:nfs4_locku_prepare+0x35/0xc2 Code: 89 f2 48 89 fd 48 c7 c7 68 69 ef b5 53 48 8b 8e 90 00 00 00 48 89 f3 RSP: 0018:ffffbbafc006bdb8 EFLAGS: 00010246 RAX: 000000000000004b RBX: ffff9b964fc1fa00 RCX: 0000000000000000 RDX: 0000000000000000 RSI: fffffffffffffff4 RDI: ffff9ba53fddbf40 RBP: ffff9ba539934000 R08: 0000000000000000 R09: ffffbbafc006bc38 R10: ffffffffb6b689c8 R11: 0000000000000003 R12: ffff9ba539934030 R13: 0000000000000001 R14: 0000000004248060 R15: ffffffffb56d1c30 FS: 0000000000000000(0000) GS:ffff9ba5881f0000(0000) knlGS:00000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000000000000c CR3: 000000093f244000 CR4: 00000000000006f0 Call Trace: <TASK> __rpc_execute+0xbc/0x480 rpc_async_schedule+0x2f/0x40 process_one_work+0x232/0x5d0 worker_thread+0x1da/0x3d0 ? __pfx_worker_thread+0x10/0x10 kthread+0x10d/0x240 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x34/0x50 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 </TASK> Modules linked in: CR2: 000000000000000c ---[ end trace 0000000000000000 ]---
Free the allocated nfs4_unlockdata when nfs_get_lock_context() fails and return NULL to terminate subsequent rpc_run_task, preventing NULL pointer dereference.
Fixes: f30cb757f680 ("NFS: Always wait for I/O completion before unlock") Signed-off-by: Li Lingfeng lilingfeng3@huawei.com Reviewed-by: Jeff Layton jlayton@kernel.org Link: https://lore.kernel.org/r/20250417072508.3850532-1-lilingfeng3@huawei.com Signed-off-by: Trond Myklebust trond.myklebust@hammerspace.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/nfs/nfs4proc.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index 632cea3fb91da..3477da3c2190e 100644 --- a/fs/nfs/nfs4proc.c +++ b/fs/nfs/nfs4proc.c @@ -6573,10 +6573,18 @@ static struct nfs4_unlockdata *nfs4_alloc_unlockdata(struct file_lock *fl, struct nfs4_unlockdata *p; struct nfs4_state *state = lsp->ls_state; struct inode *inode = state->inode; + struct nfs_lock_context *l_ctx;
p = kzalloc(sizeof(*p), GFP_NOFS); if (p == NULL) return NULL; + l_ctx = nfs_get_lock_context(ctx); + if (!IS_ERR(l_ctx)) { + p->l_ctx = l_ctx; + } else { + kfree(p); + return NULL; + } p->arg.fh = NFS_FH(inode); p->arg.fl = &p->fl; p->arg.seqid = seqid; @@ -6584,7 +6592,6 @@ static struct nfs4_unlockdata *nfs4_alloc_unlockdata(struct file_lock *fl, p->lsp = lsp; /* Ensure we don't close file until we're done freeing locks! */ p->ctx = get_nfs_open_context(ctx); - p->l_ctx = nfs_get_lock_context(ctx); locks_init_lock(&p->fl); locks_copy_lock(&p->fl, fl); p->server = NFS_SERVER(inode);