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riscv: kprobes: Fix probe address validation

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When adding a kprobe such as "p:probe/tcp_sendmsg _text+15392192",
arch_check_kprobe would start iterating all instructions starting from
_text until the probed address. Not only is this very inefficient, but
literal values in there (e.g. left by function patching) are
misinterpreted in a way that causes a desync.

Fix this by doing it like x86: start the iteration at the closest
preceding symbol instead of the given starting point.

Fixes: 87f48c7ccc ("riscv: kprobe: Fixup kernel panic when probing an illegal position")
Signed-off-by: Fabian Vogt <fvogt@suse.de>
Signed-off-by: Marvin Friedrich <marvin.friedrich@suse.com>
Acked-by: Guo Ren <guoren@kernel.org>
Link: https://lore.kernel.org/r/6191817.lOV4Wx5bFT@fvogt-thinkpad
Signed-off-by: Paul Walmsley <pjw@kernel.org>
This commit is contained in:
Fabian Vogt
2025-09-10 17:25:13 +02:00
committed by Paul Walmsley
parent c199745d3a
commit 9e68bd803f
1 changed files with 9 additions and 4 deletions
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13
arch/riscv/kernel/probes/kprobes.c
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@@ -49,10 +49,15 @@ static void __kprobes arch_simulate_insn(struct kprobe *p, struct pt_regs *regs)
post_kprobe_handler(p, kcb, regs); post_kprobe_handler(p, kcb, regs);
} }
static bool __kprobes arch_check_kprobe(struct kprobe *p) static bool __kprobes arch_check_kprobe(unsigned long addr)
{ {
unsigned long tmp = (unsigned long)p->addr - p->offset; unsigned long tmp, offset;
unsigned long addr = (unsigned long)p->addr;
/* start iterating at the closest preceding symbol */
if (!kallsyms_lookup_size_offset(addr, NULL, &offset))
return false;
tmp = addr - offset;
while (tmp <= addr) { while (tmp <= addr) {
if (tmp == addr) if (tmp == addr)
@@ -71,7 +76,7 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
if ((unsigned long)insn & 0x1) if ((unsigned long)insn & 0x1)
return -EILSEQ; return -EILSEQ;
if (!arch_check_kprobe(p)) if (!arch_check_kprobe((unsigned long)p->addr))
return -EILSEQ; return -EILSEQ;
/* copy instruction */ /* copy instruction */