CVE-2024-26645

CVE-2024-26645 is a medium-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 5.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Description

In the Linux kernel, the following vulnerability has been resolved: tracing: Ensure visibility when inserting an element into tracing_map Running the following two commands in parallel on a multi-processor AArch64 machine can sporadically produce an unexpected warning about duplicate histogram entries: $ while true; do echo hist:key=id.syscall:val=hitcount > \ /sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/trigger cat /sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/hist sleep 0.001 done $ stress-ng --sysbadaddr $(nproc) The warning looks as follows: [ 2911.172474] ------------[ cut here ]------------ [ 2911.173111] Duplicates detected: 1 [ 2911.173574] WARNING: CPU: 2 PID: 12247 at kernel/trace/tracing_map.c:983 tracing_map_sort_entries+0x3e0/0x408 [ 2911.174702] Modules linked in: iscsi_ibft(E) iscsi_boot_sysfs(E) rfkill(E) af_packet(E) nls_iso8859_1(E) nls_cp437(E) vfat(E) fat(E) ena(E) tiny_power_button(E) qemu_fw_cfg(E) button(E) fuse(E) efi_pstore(E) ip_tables(E) x_tables(E) xfs(E) libcrc32c(E) aes_ce_blk(E) aes_ce_cipher(E) crct10dif_ce(E) polyval_ce(E) polyval_generic(E) ghash_ce(E) gf128mul(E) sm4_ce_gcm(E) sm4_ce_ccm(E) sm4_ce(E) sm4_ce_cipher(E) sm4(E) sm3_ce(E) sm3(E) sha3_ce(E) sha512_ce(E) sha512_arm64(E) sha2_ce(E) sha256_arm64(E) nvme(E) sha1_ce(E) nvme_core(E) nvme_auth(E) t10_pi(E) sg(E) scsi_mod(E) scsi_common(E) efivarfs(E) [ 2911.174738] Unloaded tainted modules: cppc_cpufreq(E):1 [ 2911.180985] CPU: 2 PID: 12247 Comm: cat Kdump: loaded Tainted: G E 6.7.0-default #2 1b58bbb22c97e4399dc09f92d309344f69c44a01 [ 2911.182398] Hardware name: Amazon EC2 c7g.8xlarge/, BIOS 1.0 11/1/2018 [ 2911.183208] pstate: 61400005 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--) [ 2911.184038] pc : tracing_map_sort_entries+0x3e0/0x408 [ 2911.184667] lr : tracing_map_sort_entries+0x3e0/0x408 [ 2911.185310] sp : ffff8000a1513900 [ 2911.185750] x29: ffff8000a1513900 x28: ffff0003f272fe80 x27: 0000000000000001 [ 2911.186600] x26: ffff0003f272fe80 x25: 0000000000000030 x24: 0000000000000008 [ 2911.187458] x23: ffff0003c5788000 x22: ffff0003c16710c8 x21: ffff80008017f180 [ 2911.188310] x20: ffff80008017f000 x19: ffff80008017f180 x18: ffffffffffffffff [ 2911.189160] x17: 0000000000000000 x16: 0000000000000000 x15: ffff8000a15134b8 [ 2911.190015] x14: 0000000000000000 x13: 205d373432323154 x12: 5b5d313131333731 [ 2911.190844] x11: 00000000fffeffff x10: 00000000fffeffff x9 : ffffd1b78274a13c [ 2911.191716] x8 : 000000000017ffe8 x7 : c0000000fffeffff x6 : 000000000057ffa8 [ 2911.192554] x5 : ffff0012f6c24ec0 x4 : 0000000000000000 x3 : ffff2e5b72b5d000 [ 2911.193404] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff0003ff254480 [ 2911.194259] Call trace: [ 2911.194626] tracing_map_sort_entries+0x3e0/0x408 [ 2911.195220] hist_show+0x124/0x800 [ 2911.195692] seq_read_iter+0x1d4/0x4e8 [ 2911.196193] seq_read+0xe8/0x138 [ 2911.196638] vfs_read+0xc8/0x300 [ 2911.197078] ksys_read+0x70/0x108 [ 2911.197534] __arm64_sys_read+0x24/0x38 [ 2911.198046] invoke_syscall+0x78/0x108 [ 2911.198553] el0_svc_common.constprop.0+0xd0/0xf8 [ 2911.199157] do_el0_svc+0x28/0x40 [ 2911.199613] el0_svc+0x40/0x178 [ 2911.200048] el0t_64_sync_handler+0x13c/0x158 [ 2911.200621] el0t_64_sync+0x1a8/0x1b0 [ 2911.201115] ---[ end trace 0000000000000000 ]--- The problem appears to be caused by CPU reordering of writes issued from __tracing_map_insert(). The check for the presence of an element with a given key in this function is: val = READ_ONCE(entry->val); if (val && keys_match(key, val->key, map->key_size)) ... The write of a new entry is: elt = get_free_elt(map); memcpy(elt->key, key, map->key_size); entry->val = elt; The "memcpy(elt->key, key, map->key_size);" and "entry->val = elt;" stores may become visible in the reversed order on another CPU. This second CPU might then incorrectly determine that a new key doesn't match an already present val->key and subse ---truncated---

Frequently asked questions

What is CVE-2024-26645?
In the Linux kernel, the following vulnerability has been resolved: tracing: Ensure visibility when inserting an element into tracing_map Running the following two commands in parallel on a multi-processor AArch64 machine can sporadically produce an unexpected warning about duplicate histogram entries: $ while true; do echo hist:key=id.syscall:val=hitcount > \ /sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/trigger cat /sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/hist sleep 0.001 done $ stress-ng --sysbadaddr $(nproc) The warning looks as follows: [ 2911.172474] ------------[ cut here ]------------ [ 2911.173111] Duplicates detected: 1 [ 2911.173574] WARNING: CPU: 2 PID: 12247 at kernel/trace/tracing_map.c:983 tracing_map_sort_entries+0x3e0/0x408 [ 2911.174702] Modules linked in: iscsi_ibft(E) iscsi_boot_sysfs(E) rfkill(E) af_packet(E) nls_iso8859_1(E) nls_cp437(E) vfat(E) fat(E) ena(E) tiny_power_button(E) qemu_fw_cfg(E) button(E) fuse(E) efi_pstore(E) ip_tables(E) x_tables(E) xfs(E) libcrc32c(E) aes_ce_blk(E) aes_ce_cipher(E) crct10dif_ce(E) polyval_ce(E) polyval_generic(E) ghash_ce(E) gf128mul(E) sm4_ce_gcm(E) sm4_ce_ccm(E) sm4_ce(E) sm4_ce_cipher(E) sm4(E) sm3_ce(E) sm3(E) sha3_ce(E) sha512_ce(E) sha512_arm64(E) sha2_ce(E) sha256_arm64(E) nvme(E) sha1_ce(E) nvme_core(E) nvme_auth(E) t10_pi(E) sg(E) scsi_mod(E) scsi_common(E) efivarfs(E) [ 2911.174738] Unloaded tainted modules: cppc_cpufreq(E):1 [ 2911.180985] CPU: 2 PID: 12247 Comm: cat Kdump: loaded Tainted: G E 6.7.0-default #2 1b58bbb22c97e4399dc09f92d309344f69c44a01 [ 2911.182398] Hardware name: Amazon EC2 c7g.8xlarge/, BIOS 1.0 11/1/2018 [ 2911.183208] pstate: 61400005 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--) [ 2911.184038] pc : tracing_map_sort_entries+0x3e0/0x408 [ 2911.184667] lr : tracing_map_sort_entries+0x3e0/0x408 [ 2911.185310] sp : ffff8000a1513900 [ 2911.185750] x29: ffff8000a1513900 x28: ffff0003f272fe80 x27: 0000000000000001 [ 2911.186600] x26: ffff0003f272fe80 x25: 0000000000000030 x24: 0000000000000008 [ 2911.187458] x23: ffff0003c5788000 x22: ffff0003c16710c8 x21: ffff80008017f180 [ 2911.188310] x20: ffff80008017f000 x19: ffff80008017f180 x18: ffffffffffffffff [ 2911.189160] x17: 0000000000000000 x16: 0000000000000000 x15: ffff8000a15134b8 [ 2911.190015] x14: 0000000000000000 x13: 205d373432323154 x12: 5b5d313131333731 [ 2911.190844] x11: 00000000fffeffff x10: 00000000fffeffff x9 : ffffd1b78274a13c [ 2911.191716] x8 : 000000000017ffe8 x7 : c0000000fffeffff x6 : 000000000057ffa8 [ 2911.192554] x5 : ffff0012f6c24ec0 x4 : 0000000000000000 x3 : ffff2e5b72b5d000 [ 2911.193404] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff0003ff254480 [ 2911.194259] Call trace: [ 2911.194626] tracing_map_sort_entries+0x3e0/0x408 [ 2911.195220] hist_show+0x124/0x800 [ 2911.195692] seq_read_iter+0x1d4/0x4e8 [ 2911.196193] seq_read+0xe8/0x138 [ 2911.196638] vfs_read+0xc8/0x300 [ 2911.197078] ksys_read+0x70/0x108 [ 2911.197534] __arm64_sys_read+0x24/0x38 [ 2911.198046] invoke_syscall+0x78/0x108 [ 2911.198553] el0_svc_common.constprop.0+0xd0/0xf8 [ 2911.199157] do_el0_svc+0x28/0x40 [ 2911.199613] el0_svc+0x40/0x178 [ 2911.200048] el0t_64_sync_handler+0x13c/0x158 [ 2911.200621] el0t_64_sync+0x1a8/0x1b0 [ 2911.201115] ---[ end trace 0000000000000000 ]--- The problem appears to be caused by CPU reordering of writes issued from __tracing_map_insert(). The check for the presence of an element with a given key in this function is: val = READ_ONCE(entry->val); if (val && keys_match(key, val->key, map->key_size)) ... The write of a new entry is: elt = get_free_elt(map); memcpy(elt->key, key, map->key_size); entry->val = elt; The "memcpy(elt->key, key, map->key_size);" and "entry->val = elt;" stores may become visible in the reversed order on another CPU. This second CPU might then incorrectly determine that a new key doesn't match an already present val->key and subse ---truncated---
How severe is CVE-2024-26645?
CVE-2024-26645 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2024-26645 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2024-26645?
CVE-2024-26645 primarily affects Linux Linux Kernel. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2024-26645?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2024-26645 have an EU (EUVD) identifier?
Yes. CVE-2024-26645 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-23907.
When was CVE-2024-26645 published?
CVE-2024-26645 was published on 2024-03-26 and last updated on 2026-06-17.

References

Affected products (3)

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