6.1-stable review patch. If anyone has any objections, please let me know.
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From: Fabian Vogt fvogt@suse.de
[ Upstream commit 9e68bd803fac49274fde914466fd3b07c4d602c8 ]
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: 87f48c7ccc73 ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- arch/riscv/kernel/probes/kprobes.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/arch/riscv/kernel/probes/kprobes.c b/arch/riscv/kernel/probes/kprobes.c index cca2b3a2135ad..f4836ef13e9bb 100644 --- a/arch/riscv/kernel/probes/kprobes.c +++ b/arch/riscv/kernel/probes/kprobes.c @@ -48,10 +48,15 @@ static void __kprobes arch_simulate_insn(struct kprobe *p, struct pt_regs *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 addr = (unsigned long)p->addr; + unsigned long tmp, offset; + + /* start iterating at the closest preceding symbol */ + if (!kallsyms_lookup_size_offset(addr, NULL, &offset)) + return false; + + tmp = addr - offset;
while (tmp <= addr) { if (tmp == addr) @@ -70,7 +75,7 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) if ((unsigned long)insn & 0x1) return -EILSEQ;
- if (!arch_check_kprobe(p)) + if (!arch_check_kprobe((unsigned long)p->addr)) return -EILSEQ;
/* copy instruction */