Description

In the Linux kernel, the following vulnerability has been resolved:

fs/9p: fix NULL pointer dereference on mkdir

When a 9p tree was mounted with option 'posixacl', parent directory had a
default ACL set for its subdirectories, e.g.:

setfacl -m default:group:simpsons:rwx parentdir

then creating a subdirectory crashed 9p client, as v9fs_fid_add() call in
function v9fs_vfs_mkdir_dotl() sets the passed 'fid' pointer to NULL
(since dafbe689736) even though the subsequent v9fs_set_create_acl() call
expects a valid non-NULL 'fid' pointer:

[ 37.273191] BUG: kernel NULL pointer dereference, address: 0000000000000000
...
[ 37.322338] Call Trace:
[ 37.323043]
[ 37.323621] ? __die (arch/x86/kernel/dumpstack.c:421 arch/x86/kernel/dumpstack.c:434)
[ 37.324448] ? page_fault_oops (arch/x86/mm/fault.c:714)
[ 37.325532] ? search_module_extables (kernel/module/main.c:3733)
[ 37.326742] ? p9_client_walk (net/9p/client.c:1165) 9pnet
[ 37.328006] ? search_bpf_extables (kernel/bpf/core.c:804)
[ 37.329142] ? exc_page_fault (./arch/x86/include/asm/paravirt.h:686 arch/x86/mm/fault.c:1488 arch/x86/mm/fault.c:1538)
[ 37.330196] ? asm_exc_page_fault (./arch/x86/include/asm/idtentry.h:574)
[ 37.331330] ? p9_client_walk (net/9p/client.c:1165) 9pnet
[ 37.332562] ? v9fs_fid_xattr_get (fs/9p/xattr.c:30) 9p
[ 37.333824] v9fs_fid_xattr_set (fs/9p/fid.h:23 fs/9p/xattr.c:121) 9p
[ 37.335077] v9fs_set_acl (fs/9p/acl.c:276) 9p
[ 37.336112] v9...

Classification

CVE ID: CVE-2025-22070

Affected Products

Vendor: Linux

Product: Linux, Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.02% (probability of being exploited)

EPSS Percentile: 2.91% (scored less or equal to compared to others)

EPSS Date: 2025-04-20 (when was this score calculated)

References

https://nvd.nist.gov/vuln/detail/CVE-2025-22070
https://git.kernel.org/stable/c/8522051c58d68146b93e8a5ba9987e83b3d64e7b
https://git.kernel.org/stable/c/2139dea5c53e3bb63ac49a6901c85e525a80ee8a
https://git.kernel.org/stable/c/6517b395cb1e43fbf3962dd93e6fb4a5e5ab100e
https://git.kernel.org/stable/c/3f61ac7c65bdb26accb52f9db66313597e759821

Timeline