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CVE-2026-98380

Linux: net/sched: reject IDR error pointers when deleting actions

Linux LinuxOperating systems
Open in ThreatlineRecord JSON
CVSS
NoneNot scored
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.18%Chance of exploitation activity in the next 30 days, higher than 6% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in39b751a210bf61a374afa82749afc7a77a08bf1dAlso 6bf076258aac4e0af69ef317656c31ce6444d647, 6c9f07bf8800171de2cd3f02815cebe1f4d45f2d and 2 moreCVE List
Published9 Oct 2026Updated 19 Oct 2026CVE List

What fixes it

  • 39b751a210bf61a374afa82749afc7a77a08bf1dLinuxCVE List
  • 6bf076258aac4e0af69ef317656c31ce6444d647LinuxCVE List
  • 6c9f07bf8800171de2cd3f02815cebe1f4d45f2dLinuxCVE List
  • 259caa711b7688365676442e2fdb286b8aceaa80LinuxCVE List
  • 968550a439f64bd1a6c0d88efb92e4f082f84a26LinuxCVE List

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Description

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.

Text from CVE List

Affected versions 18

  • Linuxaffected: 0190c1d452a91c38a3462abdd81752be1b9006a8 before 39b751a210bf61a374afa82749afc7a77a08bf1dCVE List
  • Linuxaffected: 0190c1d452a91c38a3462abdd81752be1b9006a8 before dd80a7519824b72c8fcfd3cc50cb93f7e2d90923CVE List
  • Linuxaffected: 0190c1d452a91c38a3462abdd81752be1b9006a8 before 6bf076258aac4e0af69ef317656c31ce6444d647CVE List
  • Linuxaffected: 0190c1d452a91c38a3462abdd81752be1b9006a8 before 6c9f07bf8800171de2cd3f02815cebe1f4d45f2dCVE List
  • Linuxaffected: 0190c1d452a91c38a3462abdd81752be1b9006a8 before 259caa711b7688365676442e2fdb286b8aceaa80CVE List
  • Linuxaffected: 0190c1d452a91c38a3462abdd81752be1b9006a8 before 968550a439f64bd1a6c0d88efb92e4f082f84a26CVE List
  • Linuxaffected: 0190c1d452a91c38a3462abdd81752be1b9006a8 before a9551f26287debe6d8aa6e8841974661065b975fCVE List
  • Linuxaffected: 0190c1d452a91c38a3462abdd81752be1b9006a8 before c82b797abe668d0b668601a93ba2c0b071a63574CVE List
  • Linuxaffected: 4.19CVE List
  • Linuxunaffected: all versions before 4.19CVE List
  • Linuxunaffected: 5.10.271 through 5.10.*CVE List
  • Linuxunaffected: 5.15.222 through 5.15.*CVE List
  • Linuxunaffected: 6.1.189 through 6.1.*CVE List
  • Linuxunaffected: 6.6.158 through 6.6.*CVE List
  • Linuxunaffected: 6.12.112 through 6.12.*CVE List
  • Linuxunaffected: 6.18.55 through 6.18.*CVE List
  • Linuxunaffected: 7.2.9 through 7.2.*CVE List
  • Linuxunaffected: 7.3CVE List

References 8