tjh.dev / kernel
Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
1
fork

Configure Feed

Select the types of activity you want to include in your feed.

riscv: stacktrace: Disable KASAN checks for non-current tasks

Unwinding the stack of a task other than current, KASAN would report
"BUG: KASAN: out-of-bounds in walk_stackframe+0x41c/0x460"

There is a same issue on x86 and has been resolved by the commit
84936118bdf3 ("x86/unwind: Disable KASAN checks for non-current tasks")
The solution could be applied to RISC-V too.

This patch also can solve the issue:
https://seclists.org/oss-sec/2025/q4/23

Fixes: 5d8544e2d007 ("RISC-V: Generic library routines and assembly")
Co-developed-by: Jiakai Xu <xujiakai2025@iscas.ac.cn>
Signed-off-by: Jiakai Xu <xujiakai2025@iscas.ac.cn>
Signed-off-by: Chunyan Zhang <zhangchunyan@iscas.ac.cn>
Link: https://lore.kernel.org/r/20251022072608.743484-1-zhangchunyan@iscas.ac.cn
[pjw@kernel.org: clean up checkpatch issues]
Signed-off-by: Paul Walmsley <pjw@kernel.org>

authored by

Chunyan Zhang and committed by
Paul Walmsley 060ea84a dcb6fa37

+19 -2
+19 -2
arch/riscv/kernel/stacktrace.c
··· 16 16 17 17 #ifdef CONFIG_FRAME_POINTER 18 18 19 + /* 20 + * This disables KASAN checking when reading a value from another task's stack, 21 + * since the other task could be running on another CPU and could have poisoned 22 + * the stack in the meantime. 23 + */ 24 + #define READ_ONCE_TASK_STACK(task, x) \ 25 + ({ \ 26 + unsigned long val; \ 27 + unsigned long addr = x; \ 28 + if ((task) == current) \ 29 + val = READ_ONCE(addr); \ 30 + else \ 31 + val = READ_ONCE_NOCHECK(addr); \ 32 + val; \ 33 + }) 34 + 19 35 extern asmlinkage void handle_exception(void); 20 36 extern unsigned long ret_from_exception_end; 21 37 ··· 85 69 fp = frame->ra; 86 70 pc = regs->ra; 87 71 } else { 88 - fp = frame->fp; 89 - pc = ftrace_graph_ret_addr(current, &graph_idx, frame->ra, 72 + fp = READ_ONCE_TASK_STACK(task, frame->fp); 73 + pc = READ_ONCE_TASK_STACK(task, frame->ra); 74 + pc = ftrace_graph_ret_addr(current, &graph_idx, pc, 90 75 &frame->ra); 91 76 if (pc >= (unsigned long)handle_exception && 92 77 pc < (unsigned long)&ret_from_exception_end) {