| From d31e47ab174e48ec43e1b8b5f5abf0f105e95ac4 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Sat, 9 Dec 2023 15:49:15 +0800 |
| Subject: LoongArch: Preserve syscall nr across execve() |
| |
| From: Hengqi Chen <hengqi.chen@gmail.com> |
| |
| [ Upstream commit d6c5f06e46a836e6a70c7cfd95bb38a67d9252ec ] |
| |
| Currently, we store syscall nr in pt_regs::regs[11] and syscall execve() |
| accidentally overrides it during its execution: |
| |
| sys_execve() |
| -> do_execve() |
| -> do_execveat_common() |
| -> bprm_execve() |
| -> exec_binprm() |
| -> search_binary_handler() |
| -> load_elf_binary() |
| -> ELF_PLAT_INIT() |
| |
| ELF_PLAT_INIT() reset regs[11] to 0, so in syscall_exit_to_user_mode() |
| we later get a wrong syscall nr. This breaks tools like execsnoop since |
| it relies on execve() tracepoints. |
| |
| Skip pt_regs::regs[11] reset in ELF_PLAT_INIT() to fix the issue. |
| |
| Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com> |
| Signed-off-by: Huacai Chen <chenhuacai@loongson.cn> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| arch/loongarch/include/asm/elf.h | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| diff --git a/arch/loongarch/include/asm/elf.h b/arch/loongarch/include/asm/elf.h |
| index b9a4ab54285c..9b16a3b8e706 100644 |
| --- a/arch/loongarch/include/asm/elf.h |
| +++ b/arch/loongarch/include/asm/elf.h |
| @@ -293,7 +293,7 @@ extern const char *__elf_platform; |
| #define ELF_PLAT_INIT(_r, load_addr) do { \ |
| _r->regs[1] = _r->regs[2] = _r->regs[3] = _r->regs[4] = 0; \ |
| _r->regs[5] = _r->regs[6] = _r->regs[7] = _r->regs[8] = 0; \ |
| - _r->regs[9] = _r->regs[10] = _r->regs[11] = _r->regs[12] = 0; \ |
| + _r->regs[9] = _r->regs[10] /* syscall n */ = _r->regs[12] = 0; \ |
| _r->regs[13] = _r->regs[14] = _r->regs[15] = _r->regs[16] = 0; \ |
| _r->regs[17] = _r->regs[18] = _r->regs[19] = _r->regs[20] = 0; \ |
| _r->regs[21] = _r->regs[22] = _r->regs[23] = _r->regs[24] = 0; \ |
| -- |
| 2.43.0 |
| |
