{"id":"CVE-2022-49888","title":"arm64: entry: avoid kprobe recursion","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\narm64: entry: avoid kprobe recursion\n\nThe cortex_a76_erratum_1463225_debug_handler() function is called when\nhandling debug exceptions (and synchronous exceptions from …","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 6459b8469753e9feaa8b34691d097cffad905931 < 71d6c33fe223255f4416a01514da2c0bc3e283e7","Linux >= 6459b8469753e9feaa8b34691d097cffad905931 < db66629d43b2d12cb43b004a4ca6be1d03228e97","Linux >= 6459b8469753e9feaa8b34691d097cffad905931 < 024f4b2e1f874934943eb2d3d288ebc52c79f55c","Linux 5.12"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-11-05T19:51:10.485408Z"},"published":"2025-05-01","updated":"2026-11-05","sourceUpdated":"2026-11-05T20:00:10.778Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2022-49888","references":[{"url":"https://git.kernel.org/stable/c/71d6c33fe223255f4416a01514da2c0bc3e283e7"},{"url":"https://git.kernel.org/stable/c/db66629d43b2d12cb43b004a4ca6be1d03228e97"},{"url":"https://git.kernel.org/stable/c/024f4b2e1f874934943eb2d3d288ebc52c79f55c"}],"tags":["cve.org"],"epss":0.00247,"epssPercentile":0.16129,"ingestedAt":"2026-11-05T22:38:31.622Z","slug":"CVE-2022-49888","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\narm64: entry: avoid kprobe recursion\n\nThe cortex_a76_erratum_1463225_debug_handler() function is called when\nhandling debug exceptions (and synchronous exceptions from BRK\ninstructions), and so is called when a probed function executes. If the\ncompiler does not inline cortex_a76_erratum_1463225_debug_handler(), it\ncan be probed.\n\nIf cortex_a76_erratum_1463225_debug_handler() is probed, any debug\nexception or software breakpoint exception will result in recursive\nexceptions leading to a stack overflow. This can be triggered with the\nftrace multiple_probes selftest, and as per the example splat below.\n\nThis is a regression caused by commit:\n\n  6459b8469753e9fe (\"arm64: entry: consolidate Cortex-A76 erratum 1463225 workaround\")\n\n... which removed the NOKPROBE_SYMBOL() annotation associated with the\nfunction.\n\nMy intent was that cortex_a76_erratum_1463225_debug_handler() would be\ninlined into its caller, el1_dbg(), which is marked noinstr and cannot\nbe probed. Mark cortex_a76_erratum_1463225_debug_handler() as\n__always_inline to ensure this.\n\nExample splat prior to this patch (with recursive entries elided):\n\n| # echo p cortex_a76_erratum_1463225_debug_handler > /sys/kernel/debug/tracing/kprobe_events\n| # echo p do_el0_svc >> /sys/kernel/debug/tracing/kprobe_events\n| # echo 1 > /sys/kernel/debug/tracing/events/kprobes/enable\n| Insufficient stack space to handle exception!\n| ESR: 0x0000000096000047 -- DABT (current EL)\n| FAR: 0xffff800009cefff0\n| Task stack:     [0xffff800009cf0000..0xffff800009cf4000]\n| IRQ stack:      [0xffff800008000000..0xffff800008004000]\n| Overflow stack: [0xffff00007fbc00f0..0xffff00007fbc10f0]\n| CPU: 0 PID: 145 Comm: sh Not tainted 6.0.0 #2\n| Hardware name: linux,dummy-virt (DT)\n| pstate: 604003c5 (nZCv DAIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)\n| pc : arm64_enter_el1_dbg+0x4/0x20\n| lr : el1_dbg+0x24/0x5c\n| sp : ffff800009cf0000\n| x29: ffff800009cf0000 x28: ffff000002c74740 x27: 0000000000000000\n| x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000\n| x23: 00000000604003c5 x22: ffff80000801745c x21: 0000aaaac95ac068\n| x20: 00000000f2000004 x19: ffff800009cf0040 x18: 0000000000000000\n| x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000\n| x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000\n| x11: 0000000000000010 x10: ffff800008c87190 x9 : ffff800008ca00d0\n| x8 : 000000000000003c x7 : 0000000000000000 x6 : 0000000000000000\n| x5 : 0000000000000000 x4 : 0000000000000000 x3 : 00000000000043a4\n| x2 : 00000000f2000004 x1 : 00000000f2000004 x0 : ffff800009cf0040\n| Kernel panic - not syncing: kernel stack overflow\n| CPU: 0 PID: 145 Comm: sh Not tainted 6.0.0 #2\n| Hardware name: linux,dummy-virt (DT)\n| Call trace:\n|  dump_backtrace+0xe4/0x104\n|  show_stack+0x18/0x4c\n|  dump_stack_lvl+0x64/0x7c\n|  dump_stack+0x18/0x38\n|  panic+0x14c/0x338\n|  test_taint+0x0/0x2c\n|  panic_bad_stack+0x104/0x118\n|  handle_bad_stack+0x34/0x48\n|  __bad_stack+0x78/0x7c\n|  arm64_enter_el1_dbg+0x4/0x20\n|  el1h_64_sync_handler+0x40/0x98\n|  el1h_64_sync+0x64/0x68\n|  cortex_a76_erratum_1463225_debug_handler+0x0/0x34\n...\n|  el1h_64_sync_handler+0x40/0x98\n|  el1h_64_sync+0x64/0x68\n|  cortex_a76_erratum_1463225_debug_handler+0x0/0x34\n...\n|  el1h_64_sync_handler+0x40/0x98\n|  el1h_64_sync+0x64/0x68\n|  cortex_a76_erratum_1463225_debug_handler+0x0/0x34\n|  el1h_64_sync_handler+0x40/0x98\n|  el1h_64_sync+0x64/0x68\n|  do_el0_svc+0x0/0x28\n|  el0t_64_sync_handler+0x84/0xf0\n|  el0t_64_sync+0x18c/0x190\n| Kernel Offset: disabled\n| CPU features: 0x0080,00005021,19001080\n| Memory Limit: none\n| ---[ end Kernel panic - not syncing: kernel stack overflow ]---\n\nWith this patch, cortex_a76_erratum_1463225_debug_handler() is inlined\ninto el1_dbg(), and el1_dbg() cannot be probed:\n\n| # echo p cortex_a76_erratum_1463225_debug_handler > /sys/kernel/debug/tracing/kprobe_events\n| sh: write error: No such file or directory\n| # grep -w cortex_a76_errat\n---truncated---\n\n## Affected\n\n- `Linux >= 6459b8469753e9feaa8b34691d097cffad905931 < 71d6c33fe223255f4416a01514da2c0bc3e283e7`\n- `Linux >= 6459b8469753e9feaa8b34691d097cffad905931 < db66629d43b2d12cb43b004a4ca6be1d03228e97`\n- `Linux >= 6459b8469753e9feaa8b34691d097cffad905931 < 024f4b2e1f874934943eb2d3d288ebc52c79f55c`\n- `Linux 5.12`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}