GHSA-J546-37MC-3C35
Vulnerability from github – Published: 2026-10-09 09:31 – Updated: 2026-10-09 09:31In the Linux kernel, the following vulnerability has been resolved:
net/sched: reject IDR error pointers when deleting actions
tcf_action_delete() drops the reference held by its lookup before calling tcf_idr_delete_index() with the saved action index. An unlocked classifier can remove that action and reserve the same IDR slot with ERR_PTR(-EBUSY) in between.
tcf_idr_delete_index() only checks the lookup result for NULL. It therefore treats the reservation as a tc_action and dereferences tcfa_bindcnt. A hardware execution breakpoint was used to schedule the interleaving without changing the kernel source. KASAN reported this decoded trace:
BUG: KASAN: null-ptr-deref in tca_action_gd+0x5b9/0x1010 Read of size 4 at addr 0000000000000010 by task poc/150 Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002 RIP: tca_action_gd+0x5c0/0x1010: arch_atomic_read at arch/x86/include/asm/atomic.h:23 raw_atomic_read at include/linux/atomic/atomic-arch-fallback.h:457 atomic_read at include/linux/atomic/atomic-instrumented.h:33 tcf_idr_delete_index at net/sched/act_api.c:766 tcf_action_delete at net/sched/act_api.c:1859 tcf_del_notify at net/sched/act_api.c:2014 tca_action_gd at net/sched/act_api.c:2064 R13: 0000000000000010 R15: fffffffffffffff0 Kernel panic - not syncing: Fatal exception
R15 contains ERR_PTR(-EBUSY), and adding the tcfa_bindcnt offset produces the address in R13. With the guard applied, the same reproducer returned -ENOENT without a KASAN report or panic. Treat error pointers as absent and return -ENOENT.
{
"affected": [],
"aliases": [
"CVE-2026-98380"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-10-09T08:16:56Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: reject IDR error pointers when deleting actions\n\ntcf_action_delete() drops the reference held by its lookup before calling\ntcf_idr_delete_index() with the saved action index. An unlocked\nclassifier can remove that action and reserve the same IDR slot with\nERR_PTR(-EBUSY) in between.\n\ntcf_idr_delete_index() only checks the lookup result for NULL. It\ntherefore treats the reservation as a tc_action and dereferences\ntcfa_bindcnt. A hardware execution breakpoint was used to schedule the\ninterleaving without changing the kernel source. KASAN reported this\ndecoded trace:\n\n BUG: KASAN: null-ptr-deref in tca_action_gd+0x5b9/0x1010\n Read of size 4 at addr 0000000000000010 by task poc/150\n Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002\n RIP: tca_action_gd+0x5c0/0x1010:\n arch_atomic_read at arch/x86/include/asm/atomic.h:23\n raw_atomic_read at include/linux/atomic/atomic-arch-fallback.h:457\n atomic_read at include/linux/atomic/atomic-instrumented.h:33\n tcf_idr_delete_index at net/sched/act_api.c:766\n tcf_action_delete at net/sched/act_api.c:1859\n tcf_del_notify at net/sched/act_api.c:2014\n tca_action_gd at net/sched/act_api.c:2064\n R13: 0000000000000010 R15: fffffffffffffff0\n Kernel panic - not syncing: Fatal exception\n\nR15 contains ERR_PTR(-EBUSY), and adding the tcfa_bindcnt offset produces\nthe address in R13. With the guard applied, the same reproducer returned\n-ENOENT without a KASAN report or panic. Treat error pointers as absent\nand return -ENOENT.",
"id": "GHSA-j546-37mc-3c35",
"modified": "2026-10-09T09:31:05Z",
"published": "2026-10-09T09:31:05Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98380"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/259caa711b7688365676442e2fdb286b8aceaa80"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/39b751a210bf61a374afa82749afc7a77a08bf1d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6bf076258aac4e0af69ef317656c31ce6444d647"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6c9f07bf8800171de2cd3f02815cebe1f4d45f2d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/968550a439f64bd1a6c0d88efb92e4f082f84a26"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a9551f26287debe6d8aa6e8841974661065b975f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c82b797abe668d0b668601a93ba2c0b071a63574"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/dd80a7519824b72c8fcfd3cc50cb93f7e2d90923"
}
],
"schema_version": "1.4.0",
"severity": []
}
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