cbcvebase.
CVE-2021-46939
published 2024-02-27

CVE-2021-46939: In the Linux kernel, the following vulnerability has been resolved: tracing: Restructure trace_clock_global() to never block It was reported that a fix to the…

PriorityP420medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.25%
16.0th percentile
In the Linux kernel, the following vulnerability has been resolved: tracing: Restructure trace_clock_global() to never block It was reported that a fix to the ring buffer recursion detection would cause a hung machine when performing suspend / resume testing. The following backtrace was extracted from debugging that case: Call Trace: trace_clock_global+0x91/0xa0 __rb_reserve_next+0x237/0x460 ring_buffer_lock_reserve+0x12a/0x3f0 trace_buffer_lock_reserve+0x10/0x50 __trace_graph_return+0x1f/0x80 trace_graph_return+0xb7/0xf0 ? trace_clock_global+0x91/0xa0 ftrace_return_to_handler+0x8b/0xf0 ? pv_hash+0xa0/0xa0 return_to_handler+0x15/0x30 ? ftrace_graph_caller+0xa0/0xa0 ? trace_clock_global+0x91/0xa0 ? __rb_reserve_next+0x237/0x460 ? ring_buffer_lock_reserve+0x12a/0x3f0 ? trace_event_buffer_lock_reserve+0x3c/0x120 ? trace_event_buffer_reserve+0x6b/0xc0 ? trace_event_raw_event_device_pm_callback_start+0x125/0x2d0 ? dpm_run_callback+0x3b/0xc0 ? pm_ops_is_empty+0x50/0x50 ? platform_get_irq_byname_optional+0x90/0x90 ? trace_device_pm_callback_start+0x82/0xd0 ? dpm_run_callback+0x49/0xc0 With the following RIP: RIP: 0010:native_queued_spin_lock_slowpath+0x69/0x200 Since the fix to the recursion detection would allow a single recursion to happen while tracing, this lead to the trace_clock_global() taking a spin lock and then trying to take it again: ring_buffer_lock_reserve() { trace_clock_global() { arch_spin_lock() { queued_spin_lock_slowpath() { /* lock taken */ (something else gets traced by function graph tracer) ring_buffer_lock_reserve() { trace_clock_global() { arch_spin_lock() { queued_spin_lock_slowpath() { /* DEAD LOCK! */ Tracing should *never* block, as it can lead to strange lockups like the above. Restructure the trace_clock_global() code to instead of simply taking a lock to update the recorded "prev_time" simply use it, as two events happening on two different CPUs that calls this at the same time, really doesn't matter which one goes first. Use a try

Affected

24 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 5.10.38-1 (bookworm)linux 5.10.38-1 (bookworm)
linuxlinux
linuxlinux>= 14131f2f98ac350ee9e73faed916d2238a8b6a0d < 91ca6f6a91f679c8645d7f3307e03ce86ad518c491ca6f6a91f679c8645d7f3307e03ce86ad518c4
linuxlinux>= 14131f2f98ac350ee9e73faed916d2238a8b6a0d < 859b47a43f5a0e5b9a92b621dc6ceaad39fb5c8b859b47a43f5a0e5b9a92b621dc6ceaad39fb5c8b
linuxlinux>= 14131f2f98ac350ee9e73faed916d2238a8b6a0d < 1fca00920327be96f3318224f502e4d5460f95451fca00920327be96f3318224f502e4d5460f9545
linuxlinux>= 14131f2f98ac350ee9e73faed916d2238a8b6a0d < d43d56dbf452ccecc1ec735cd4b6840118005d7cd43d56dbf452ccecc1ec735cd4b6840118005d7c
linuxlinux>= 14131f2f98ac350ee9e73faed916d2238a8b6a0d < c64da3294a7d59a4bf6874c664c13be892f15f44c64da3294a7d59a4bf6874c664c13be892f15f44
linuxlinux>= 14131f2f98ac350ee9e73faed916d2238a8b6a0d < a33614d52e97fc8077eb0b292189ca7d964cc534a33614d52e97fc8077eb0b292189ca7d964cc534
linuxlinux>= 14131f2f98ac350ee9e73faed916d2238a8b6a0d < 6e2418576228eeb12e7ba82edb8f9500623942ff6e2418576228eeb12e7ba82edb8f9500623942ff
linuxlinux>= 14131f2f98ac350ee9e73faed916d2238a8b6a0d < 2a1bd74b8186d7938bf004f5603f25b84785f63e2a1bd74b8186d7938bf004f5603f25b84785f63e
linuxlinux>= 14131f2f98ac350ee9e73faed916d2238a8b6a0d < aafe104aa9096827a429bc1358f8260ee565b7ccaafe104aa9096827a429bc1358f8260ee565b7cc
linuxlinux_kernel>= 0 < 5.10.38-15.10.38-1
linuxlinux_kernel>= 0 < 5.10.38-15.10.38-1
linuxlinux_kernel>= 0 < 5.10.38-15.10.38-1
linuxlinux_kernel>= 0 < 5.10.38-15.10.38-1
linuxlinux_kernel>= 0 < 4.4.0-254.2884.4.0-254.288
linuxlinux_kernel>= 2.6.30 < 4.4.2694.4.269
linuxlinux_kernel>= 4.10.0 < 4.14.2334.14.233
linuxlinux_kernel>= 4.15.0 < 4.19.1914.19.191
linuxlinux_kernel>= 4.20.0 < 5.4.1185.4.118
linuxlinux_kernel>= 4.5.0 < 4.9.2694.9.269
linuxlinux_kernel>= 5.11.0 < 5.11.205.11.20
linuxlinux_kernel>= 5.12.0 < 5.12.35.12.3
linuxlinux_kernel>= 5.5.0 < 5.10.365.10.36

CVSS provenance

nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
osv5.5MEDIUM
vendor_debian5.5MEDIUM
vendor_redhat5.5MEDIUM
vendor_ubuntu5.5MEDIUM
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