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If getting acl_default fails, acl_access and acl_default will be released
simultaneously. However, acl_access will still retain a pointer pointing
to the released posix_acl, which will trigger a WARNING in
nfs3svc_release_getacl like this:
------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 26 PID: 3199 at lib/refcount.c:28
refcount_warn_saturate+0xb5/0x170
Modules linked in:
CPU: 26 UID: 0 PID: 3199 Comm: nfsd Not tainted
6.12.0-rc6-00079-g04ae226af01f-dirty #8
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.16.1-2.fc37 04/01/2014
RIP: 0010:refcount_warn_saturate+0xb5/0x170
Code: cc cc 0f b6 1d b3 20 a5 03 80 fb 01 0f 87 65 48 d8 00 83 e3 01 75
e4 48 c7 c7 c0 3b 9b 85 c6 05 97 20 a5 03 01 e8 fb 3e 30 ff <0f> 0b eb
cd 0f b6 1d 8a3
RSP: 0018:ffffc90008637cd8 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff83904fde
RDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffff88871ed36380
RBP: ffff888158beeb40 R08: 0000000000000001 R09: fffff520010c6f56
R10: ffffc90008637ab7 R11: 0000000000000001 R12: 0000000000000001
R13: ffff888140e77400 R14: ffff888140e77408 R15: ffffffff858b42c0
FS: 0000000000000000(0000) GS:ffff88871ed00000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000562384d32158 CR3: 000000055cc6a000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
? refcount_warn_saturate+0xb5/0x170
? __warn+0xa5/0x140
? refcount_warn_saturate+0xb5/0x170
? report_bug+0x1b1/0x1e0
? handle_bug+0x53/0xa0
? exc_invalid_op+0x17/0x40
? asm_exc_invalid_op+0x1a/0x20
? tick_nohz_tick_stopped+0x1e/0x40
? refcount_warn_saturate+0xb5/0x170
? refcount_warn_saturate+0xb5/0x170
nfs3svc_release_getacl+0xc9/0xe0
svc_process_common+0x5db/0xb60
? __pfx_svc_process_common+0x10/0x10
? __rcu_read_unlock+0x69/0xa0
? __pfx_nfsd_dispatch+0x10/0x10
? svc_xprt_received+0xa1/0x120
? xdr_init_decode+0x11d/0x190
svc_process+0x2a7/0x330
svc_handle_xprt+0x69d/0x940
svc_recv+0x180/0x2d0
nfsd+0x168/0x200
? __pfx_nfsd+0x10/0x10
kthread+0x1a2/0x1e0
? kthread+0xf4/0x1e0
? __pfx_kthread+0x10/0x10
ret_from_fork+0x34/0x60
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1a/0x30
</TASK>
Kernel panic - not syncing: kernel: panic_on_warn set ...
Clear acl_access/acl_default after posix_acl_release is called to prevent
UAF from being triggered.
Fixes: a257cdd0e2 ("[PATCH] NFSD: Add server support for NFSv3 ACLs.")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20241107014705.2509463-1-lilingfeng@huaweicloud.com/
Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>
Reviewed-by: Rick Macklem <rmacklem@uoguelph.ca>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.