slip: reject VJ receive packets on instances with no rstate array
Summary
| CVE | CVE-2026-45842 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-05-27 11:16:23 UTC |
| Updated | 2026-06-01 17:17:14 UTC |
| Description | In the Linux kernel, the following vulnerability has been resolved: slip: reject VJ receive packets on instances with no rstate array slhc_init() accepts rslots == 0 as a valid configuration, with the documented meaning of 'no receive compression'. In that case the allocation loop in slhc_init() is skipped, so comp->rstate stays NULL and comp->rslot_limit stays 0 (from the kzalloc of struct slcompress). The receive helpers do not defend against that configuration. slhc_uncompress() dereferences comp->rstate[x] when the VJ header carries an explicit connection ID, and slhc_remember() later assigns cs = &comp->rstate[...] after only comparing the packet's slot number to comp->rslot_limit. Because rslot_limit is 0, slot 0 passes the range check, and the code dereferences a NULL rstate. The configuration is reachable in-tree through PPP. PPPIOCSMAXCID stores its argument in a signed int, and (val >> 16) uses arithmetic shift. Passing 0xffff0000 therefore sign-extends to -1, so val2 + 1 is 0 and ppp_generic.c ends up calling slhc_init(0, 1). Because /dev/ppp open is gated by ns_capable(CAP_NET_ADMIN), the whole path is reachable from an unprivileged user namespace. Once the malformed VJ state is installed, any inbound VJ-compressed or VJ-uncompressed frame that selects slot 0 crashes the kernel in softirq context: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] RIP: 0010:slhc_uncompress (drivers/net/slip/slhc.c:519) Call Trace: <TASK> ppp_receive_nonmp_frame (drivers/net/ppp/ppp_generic.c:2466) ppp_input (drivers/net/ppp/ppp_generic.c:2359) ppp_async_process (drivers/net/ppp/ppp_async.c:492) tasklet_action_common (kernel/softirq.c:926) handle_softirqs (kernel/softirq.c:623) run_ksoftirqd (kernel/softirq.c:1055) smpboot_thread_fn (kernel/smpboot.c:160) kthread (kernel/kthread.c:436) ret_from_fork (arch/x86/kernel/process.c:164) </TASK> Reject the receive side on such instances instead of touching rstate. slhc_uncompress() falls through to its existing 'bad' label, which bumps sls_i_error and enters the toss state. slhc_remember() mirrors that with an explicit sls_i_error increment followed by slhc_toss(); the sls_i_runt counter is not used here because a missing rstate is an internal configuration state, not a runt packet. The transmit path is unaffected: the only in-tree caller that picks rslots from userspace (ppp_generic.c) still supplies tslots >= 1, and slip.c always calls slhc_init(16, 16), so comp->tstate remains valid and slhc_compress() continues to work. |
Risk And Classification
EPSS: 0.000180000 probability, percentile 0.050770000 (date 2026-06-01)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected 4ab42d78e37a294ac7bc56901d563c642e03c4ae 3d71c961febddd855d3ae9a519eeb96c8023f430 git | Not specified |
| CNA | Linux | Linux | affected 4ab42d78e37a294ac7bc56901d563c642e03c4ae 72304fec672e8aac9ee7b9c475db96b37cca8d8d git | Not specified |
| CNA | Linux | Linux | affected 4ab42d78e37a294ac7bc56901d563c642e03c4ae 4aa9eca6fda2919027dfd7a7cc69334982d89586 git | Not specified |
| CNA | Linux | Linux | affected 4ab42d78e37a294ac7bc56901d563c642e03c4ae c6980e8b1a86288167f34966fa5219031999b6f1 git | Not specified |
| CNA | Linux | Linux | affected 4ab42d78e37a294ac7bc56901d563c642e03c4ae de42f86e2cf5028a97e74c25869d1a962b13c301 git | Not specified |
| CNA | Linux | Linux | affected 4ab42d78e37a294ac7bc56901d563c642e03c4ae 9e1ff0eead073c4f46d874ad2526b7dda5465faf git | Not specified |
| CNA | Linux | Linux | affected 4ab42d78e37a294ac7bc56901d563c642e03c4ae 7b0d9e878ec2b21d99ae8051b3dda59cdb66c152 git | Not specified |
| CNA | Linux | Linux | affected 4ab42d78e37a294ac7bc56901d563c642e03c4ae e76607442d5b73e1ba6768f501ef815bb58c2c0e git | Not specified |
| CNA | Linux | Linux | affected 42fc512469e78939c1e419d3310c47de55bdcbb8 git | Not specified |
| CNA | Linux | Linux | affected df085f1cb3acd3d75408ff94f366983873bce7d2 git | Not specified |
| CNA | Linux | Linux | affected a1c3860d3c5fc62bd35f089bcb03f18a37242de9 git | Not specified |
| CNA | Linux | Linux | affected f82699de104eaf8a7ffc2849a566a94818dd8a3c git | Not specified |
| CNA | Linux | Linux | affected 354b254af5c1350de9586af75fe5a821b35bfb33 git | Not specified |
| CNA | Linux | Linux | affected 5148857f5d4c812cc918cf4627f7880521e987eb git | Not specified |
| CNA | Linux | Linux | affected 82185755d90c8047c6f4b589c39998ff3d4ca3ad git | Not specified |
| CNA | Linux | Linux | affected a50a93cc99286dc444c7e5ccc7dfb9d58c2d346d git | Not specified |
| CNA | Linux | Linux | affected 6b4fa561e26526c62636414d267342c945084f44 git | Not specified |
| CNA | Linux | Linux | affected 2.6.32.70 2.6.33 semver | Not specified |
| CNA | Linux | Linux | affected 3.2.75 3.3 semver | Not specified |
| CNA | Linux | Linux | affected 3.4.111 3.5 semver | Not specified |
| CNA | Linux | Linux | affected 3.10.96 3.11 semver | Not specified |
| CNA | Linux | Linux | affected 3.12.53 3.13 semver | Not specified |
| CNA | Linux | Linux | affected 3.14.60 3.15 semver | Not specified |
| CNA | Linux | Linux | affected 3.18.27 3.19 semver | Not specified |
| CNA | Linux | Linux | affected 4.1.17 4.2 semver | Not specified |
| CNA | Linux | Linux | affected 4.3.5 4.4 semver | Not specified |
| CNA | Linux | Linux | affected 4.4 | Not specified |
| CNA | Linux | Linux | unaffected 4.4 semver | Not specified |
| CNA | Linux | Linux | unaffected 5.10.258 5.10.* semver | Not specified |
| CNA | Linux | Linux | unaffected 5.15.209 5.15.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.1.175 6.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.6.141 6.6.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.12.91 6.12.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.18.33 6.18.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.0.10 7.0.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.1-rc1 * original_commit_for_fix | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/4aa9eca6fda2919027dfd7a7cc69334982d89586 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/72304fec672e8aac9ee7b9c475db96b37cca8d8d | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/9e1ff0eead073c4f46d874ad2526b7dda5465faf | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/de42f86e2cf5028a97e74c25869d1a962b13c301 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/e76607442d5b73e1ba6768f501ef815bb58c2c0e | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/c6980e8b1a86288167f34966fa5219031999b6f1 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/7b0d9e878ec2b21d99ae8051b3dda59cdb66c152 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/3d71c961febddd855d3ae9a519eeb96c8023f430 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.