Bug 2516885 (CVE-2026-74259)
| Summary: | CVE-2026-74259 kernel: cifs: remove all cifs files before kill super | ||
|---|---|---|---|
| Product: | [Other] Security Response | Reporter: | OSIDB Bzimport <bzimport> |
| Component: | vulnerability | Assignee: | Product Security DevOps Team <prodsec-dev> |
| Status: | NEW --- | QA Contact: | |
| Severity: | medium | Docs Contact: | |
| Priority: | medium | ||
| Version: | unspecified | CC: | rhel-process-autobot, watson-tool-maintainers |
| Target Milestone: | --- | Keywords: | Security |
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | --- | |
| Doc Text: |
A flaw was found in the Linux kernel's Common Internet File System (CIFS) implementation. A local user could trigger a null pointer dereference by unmounting a CIFS share while certain files are still being processed. This could lead to a system crash, resulting in a denial of service.
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Story Points: | --- |
| Clone Of: | Environment: | ||
| Last Closed: | Type: | --- | |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
In the Linux kernel, the following vulnerability has been resolved: cifs: remove all cifs files before kill super Cifs files may be put into fileinfo_put_wq during umounting cifs. After umount done, cifsFileInfo_put_final is called, which cause following BUG: BUG: kernel NULL pointer dereference, address: 0000000000000000 ... [ 134.222152] list_lru_add+0x64/0x1a0 [ 134.222399] ? cifs_put_tcon+0x171/0x340 [cifs] [ 134.222772] d_lru_add+0x44/0x60 [ 134.222997] dput+0x1fc/0x210 [ 134.223213] cifsFileInfo_put_final+0x11a/0x140 [cifs] [ 134.223576] process_one_work+0x17c/0x320 [ 134.223843] worker_thread+0x188/0x280 [ 134.224084] ? __pfx_worker_thread+0x10/0x10 [ 134.224366] kthread+0xcc/0x100 [ 134.224576] ? __pfx_kthread+0x10/0x10 [ 134.224827] ret_from_fork+0x30/0x50 [ 134.225063] ? __pfx_kthread+0x10/0x10 [ 134.225328] ret_from_fork_asm+0x1b/0x30 This can be reproduce by following: unshare -n bash -c " mkdir -p ${CIFS_MNT} ip netns attach root 1 ip link add eth0 type veth peer veth0 netns root ip link set eth0 up ip -n root link set veth0 up ip addr add 192.168.0.2/24 dev eth0 ip -n root addr add 192.168.0.1/24 dev veth0 ip route add default via 192.168.0.1 dev eth0 ip netns exec root sysctl net.ipv4.ip_forward=1 ip netns exec root iptables -t nat -A POSTROUTING -s 192.168.0.2 -o ${DEV} -j MASQUERADE mount -t cifs ${CIFS_PATH} ${CIFS_MNT} -o vers=3.0,sec=ntlmssp,credentials=${CIFS_CRED},rsize=65536,wsize=65536,cache=none,echo_interval=1 touch ${CIFS_MNT}/a.txt ip netns exec root iptables -t nat -D POSTROUTING -s 192.168.0.2 -o ${DEV} -j MASQUERADE " umount ${CIFS_MNT}