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bc7b086a45
Reading a word from the stack in a kretprobe crashes a risc-v kernel.
$ cd /sys/kernel/tracing/
$ echo 'r n_tty_write $stack0' > dynamic_events
$ echo 1 > events/kprobes/enable
Unable to handle kernel paging request at virtual address 0000000200000128
...
[<ffffffff80016d16>] regs_get_kernel_stack_nth+0x26/0x38
[<ffffffff80177196>] process_fetch_insn+0x3ee/0x760
[<ffffffff80177836>] kretprobe_trace_func+0x116/0x1f0
[<ffffffff8017795a>] kretprobe_dispatcher+0x4a/0x58
[<ffffffff8013572e>] kretprobe_rethook_handler+0x5e/0x90
[<ffffffff80180838>] rethook_trampoline_handler+0x70/0x108
[<ffffffff8001ba32>] arch_rethook_trampoline_callback+0x12/0x1c
[<ffffffff8001ba84>] arch_rethook_trampoline+0x48/0x94
[<ffffffff8067872a>] tty_write+0x1a/0x30
In regs_get_kernel_stack_nth, regs->sp contains an arbitrary value.
arch_rethook_trampoline saves the registers from the probed function in a
struct pt_regs. sp is not saved. Instead, sp is decremented for
arch_rethook_trampoline's local stack.
Fix this crash and save the original sp along with the other registers.
Use a0 as a temporary register, it is overwritten anyway.
Cc: stable@vger.kernel.org
Fixes:
|
||
|---|---|---|
| .. | ||
| decode-insn.c | ||
| decode-insn.h | ||
| kprobes.c | ||
| Makefile | ||
| rethook_trampoline.S | ||
| rethook.c | ||
| rethook.h | ||
| simulate-insn.c | ||
| simulate-insn.h | ||
| uprobes.c | ||