Linux Kernel: net/sched IDR error pointer deref on action delete
CVE-2026-98380 Published on October 9, 2026
net/sched: reject IDR error pointers when deleting actions
In 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.
Products Associated with CVE-2026-98380
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Affected Versions
Linux:- Version 0190c1d452a91c38a3462abdd81752be1b9006a8 and below 39b751a210bf61a374afa82749afc7a77a08bf1d is affected.
- Version 0190c1d452a91c38a3462abdd81752be1b9006a8 and below dd80a7519824b72c8fcfd3cc50cb93f7e2d90923 is affected.
- Version 0190c1d452a91c38a3462abdd81752be1b9006a8 and below 6bf076258aac4e0af69ef317656c31ce6444d647 is affected.
- Version 0190c1d452a91c38a3462abdd81752be1b9006a8 and below 6c9f07bf8800171de2cd3f02815cebe1f4d45f2d is affected.
- Version 0190c1d452a91c38a3462abdd81752be1b9006a8 and below 259caa711b7688365676442e2fdb286b8aceaa80 is affected.
- Version 0190c1d452a91c38a3462abdd81752be1b9006a8 and below 968550a439f64bd1a6c0d88efb92e4f082f84a26 is affected.
- Version 0190c1d452a91c38a3462abdd81752be1b9006a8 and below a9551f26287debe6d8aa6e8841974661065b975f is affected.
- Version 0190c1d452a91c38a3462abdd81752be1b9006a8 and below c82b797abe668d0b668601a93ba2c0b071a63574 is affected.
- Version 4.19 is affected.
- Before 4.19 is unaffected.
- Version 5.10.271, <= 5.10.* is unaffected.
- Version 5.15.222, <= 5.15.* is unaffected.
- Version 6.1.189, <= 6.1.* is unaffected.
- Version 6.6.158, <= 6.6.* is unaffected.
- Version 6.12.112, <= 6.12.* is unaffected.
- Version 6.18.55, <= 6.18.* is unaffected.
- Version 7.2.9, <= 7.2.* is unaffected.
- Version 7.3-rc5, <= * is unaffected.