CVE-2024-26796

In the Linux kernel, the following vulnerability has been resolved:
drivers: perf: ctr_get_width function for legacy is not defined With
parameters CONFIG_RISCV_PMU_LEGACY=y and CONFIG_RISCV_PMU_SBI=n linux
kernel crashes when you try perf record: $ perf record ls [ 46.749286]
Unable to handle kernel NULL pointer dereference at virtual address
0000000000000000 [ 46.750199] Oops [#1] [ 46.750342] Modules linked in: [
46.750608] CPU: 0 PID: 107 Comm: perf-exec Not tainted 6.6.0 #2 [
46.750906] Hardware name: riscv-virtio,qemu (DT) [ 46.751184] epc : 0x0 [
46.751430] ra : arch_perf_update_userpage+0x54/0x13e [ 46.751680] epc :
0000000000000000 ra : ffffffff8072ee52 sp : ff2000000022b8f0 [ 46.751958]
gp : ffffffff81505988 tp : ff6000000290d400 t0 : ff2000000022b9c0 [
46.752229] t1 : 0000000000000001 t2 : 0000000000000003 s0 :
ff2000000022b930 [ 46.752451] s1 : ff600000028fb000 a0 : 0000000000000000
a1 : ff600000028fb000 [ 46.752673] a2 : 0000000ae2751268 a3 :
00000000004fb708 a4 : 0000000000000004 [ 46.752895] a5 : 0000000000000000
a6 : 000000000017ffe3 a7 : 00000000000000d2 [ 46.753117] s2 :
ff600000028fb000 s3 : 0000000ae2751268 s4 : 0000000000000000 [ 46.753338]
s5 : ffffffff8153e290 s6 : ff600000863b9000 s7 : ff60000002961078 [
46.753562] s8 : ff60000002961048 s9 : ff60000002961058 s10:
0000000000000001 [ 46.753783] s11: 0000000000000018 t3 : ffffffffffffffff
t4 : ffffffffffffffff [ 46.754005] t5 : ff6000000292270c t6 :
ff2000000022bb30 [ 46.754179] status: 0000000200000100 badaddr:
0000000000000000 cause: 000000000000000c [ 46.754653] Code: Unable to
access instruction at 0xffffffffffffffec. [ 46.754939] —[ end trace
0000000000000000 ]— [ 46.755131] note: perf-exec[107] exited with irqs
disabled [ 46.755546] note: perf-exec[107] exited with preempt_count 4 This
happens because in the legacy case the ctr_get_width function was not
defined, but it is used in arch_perf_update_userpage. Also remove extra
check in riscv_pmu_ctr_get_width_mask