I broke this recently when I changed pt_regs->r8..r11 clearing logic in INT 80 code path.
There is a branch from SYSENTER/SYSCALL code to INT 80 code: if we fail to retrieve arg6, we return EFAULT. Before this patch, in this case we don't clear pt_regs->r8..r11. This patch fixes this. The resulting code is smaller and simpler. While at it, remove incorrect comment about syscall dispatching CALL insn: it does not use RIP-relative addressing form (the comment was meant to be "TODO: make this rip-relative", and morphed since then, dropping "TODO"). Signed-off-by: Denys Vlasenko <[email protected]> CC: Linus Torvalds <[email protected]> CC: Steven Rostedt <[email protected]> CC: Ingo Molnar <[email protected]> CC: Borislav Petkov <[email protected]> CC: "H. Peter Anvin" <[email protected]> CC: Andy Lutomirski <[email protected]> CC: Oleg Nesterov <[email protected]> CC: Frederic Weisbecker <[email protected]> CC: Alexei Starovoitov <[email protected]> CC: Will Drewry <[email protected]> CC: Kees Cook <[email protected]> CC: [email protected] CC: [email protected] --- arch/x86/entry/entry_64_compat.S | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S index 9558dac..b80f8d4 100644 --- a/arch/x86/entry/entry_64_compat.S +++ b/arch/x86/entry/entry_64_compat.S @@ -413,9 +413,7 @@ END(ia32_cstar_target) ia32_badarg: ASM_CLAC - movq $-EFAULT, %rax - jmp ia32_sysret - + movq $-EFAULT, RAX(%rsp) ia32_ret_from_sys_call: xorl %eax, %eax /* Do not leak kernel information */ movq %rax, R11(%rsp) @@ -486,9 +484,7 @@ ia32_do_call: cmpq $(IA32_NR_syscalls-1), %rax ja 1f - call *ia32_sys_call_table(, %rax, 8) /* RIP relative */ - -ia32_sysret: + call *ia32_sys_call_table(, %rax, 8) movq %rax, RAX(%rsp) 1: jmp int_ret_from_sys_call -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
