ipv4: fib: Don't dump dying fib_info in fib_leaf_notify().
In the Linux kernel, the following vulnerability has been resolved: ipv4: fib: Don't dump dying fib_info in fib_leaf_notify(). syzbot reported use-after-free in nsim_fib4_prepare_event(). [0] The problem is that the following functions call fib_info_hold() / refcount_inc() while dumping fib_info under RCU, which is unsafe. * mlxsw_sp_router_fib4_event() * rocker_router_fib_event() * nsim_fib4_prepare_event() refcount_inc_not_zero() must be used, but it would be too late there. Let's guarantee the lifetime of fib_info in fib_leaf_notify(). Note that IPv6 does not need the corresponding change since fib6_table_dump() holds fib6_table.tb6_lock. [0]: refcount_t: addition on 0; use-after-free. WARNING: lib/refcount.c:25 at refcount_warn_saturate+0x9f/0x110 lib/refcount.c:25, CPU#0: kworker/u8:15/3420 Modules linked in: CPU: 0 UID: 0 PID: 3420 Comm: kworker/u8:15 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Workqueue: netns cleanup_net RIP: 0010:refcount_warn_saturate+0x9f/0x110 lib/refcount.c:25 Code: eb 66 85 db 74 3e 83 fb 01 75 4c e8 1b f1 22 fd 48 8d 3d 84 cb f1 0a 67 48 0f b9 3a eb 4a e8 08 f1 22 fd 48 8d 3d 81 cb f1 0a <67> 48 0f b9 3a eb 37 e8 f5 f0 22 fd 48 8d 3d 7e cb f1 0a 67 48 0f RSP: 0018:ffffc9000f2c7270 EFLAGS: 00010293 RAX: ffffffff84a18858 RBX: 0000000000000002 RCX: ffff888032ff9ec0 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8f9353e0 RBP: 0000000000000000 R08: f
CVE-2026-74289
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-74289
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "c3852ef7f2f8f75a9f85a864bec1f6f5a3068eea",
"lessThan": "8bdb20b8a581495062b5879f4e9d435da648b3b0",
"versionType": "git"
},
{
"status": "affected",
"version": "c3852ef7f2f8f75a9f85a864bec1f6f5a3068eea",
"lessThan": "7907a395701b339c2d68f37456d395e953c74795",
"versionType": "git"
},
{
"status": "affected",
"version": "c3852ef7f2f8f75a9f85a864bec1f6f5a3068eea",
"lessThan": "7980a13add57f97c5da1dc961d0145a6ad2a7f98",
"versionType": "git"
},
{
"status": "affected",
"version": "c3852ef7f2f8f75a9f85a864bec1f6f5a3068eea",
"lessThan": "bea03e887db5a8a79234531faf14cf2c4d8816c3",
"versionType": "git"
},
{
"status": "affected",
"version": "c3852ef7f2f8f75a9f85a864bec1f6f5a3068eea",
"lessThan": "676482da8d938ea72c26da0fc86af2d2ec238ab2",
"versionType": "git"
},
{
"status": "affected",
"version": "c3852ef7f2f8f75a9f85a864bec1f6f5a3068eea",
"lessThan": "06b693d2eb6651a63ad85bad8673de3b7d4edd6d",
"versionType": "git"
}
],
"programFiles": [
"include/net/ip_fib.h",
"net/ipv4/fib_trie.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "4.10"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "4.10",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.1.189",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.158",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.111",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.53",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.1.5",
"versionType": "semver",
"lessThanOrEqual": "7.1.*"
},
{
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"include/net/ip_fib.h",
"net/ipv4/fib_trie.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-74289
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #33083 · Revision 1
- Added to Heist Feed
- Publisher date