Commit-ID: d4bf7078c43e11097e0d6f04d3fb999bf92c4fb0 Gitweb: http://git.kernel.org/tip/d4bf7078c43e11097e0d6f04d3fb999bf92c4fb0 Author: Josh Poimboeuf <[email protected]> AuthorDate: Tue, 17 May 2016 13:06:06 -0500 Committer: Ingo Molnar <[email protected]> CommitDate: Thu, 19 May 2016 09:12:34 +0200
x86/entry/64: Fix stack return address retrieval in thunk With CONFIG_FRAME_POINTER enabled, a thunk can pass a bad return address value to the called function. '9*8(%rsp)' actually gets the frame pointer, not the return address. The only users of the 'put_ret_addr_in_rdi' option are two functions which trace the enabling and disabling of interrupts, so this bug can result in bad debug or tracing information with CONFIG_IRQSOFF_TRACER or CONFIG_PROVE_LOCKING. Fix this by implementing the suggestion of Linus: explicitly push the frame pointer all the time and constify the stack offsets that way. This is both correct and easier to read. Reported-by: Matt Fleming <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> [ Extended the changelog a bit. ] Acked-by: Linus Torvalds <[email protected]> Cc: Alex Thorlton <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Denys Vlasenko <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Thomas Gleixner <[email protected]> Fixes: 058fb73274f9 ("x86/asm/entry: Create stack frames in thunk functions") Link: http://lkml.kernel.org/r/20160517180606.v5o7wcgdni7443ol@treble Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/entry/thunk_64.S | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/arch/x86/entry/thunk_64.S b/arch/x86/entry/thunk_64.S index 98df1fa..027aec4 100644 --- a/arch/x86/entry/thunk_64.S +++ b/arch/x86/entry/thunk_64.S @@ -8,16 +8,15 @@ #include <linux/linkage.h> #include "calling.h" #include <asm/asm.h> -#include <asm/frame.h> /* rdi: arg1 ... normal C conventions. rax is saved/restored. */ .macro THUNK name, func, put_ret_addr_in_rdi=0 .globl \name .type \name, @function \name: - FRAME_BEGIN + pushq %rbp + movq %rsp, %rbp - /* this one pushes 9 elems, the next one would be %rIP */ pushq %rdi pushq %rsi pushq %rdx @@ -29,8 +28,8 @@ pushq %r11 .if \put_ret_addr_in_rdi - /* 9*8(%rsp) is return addr on stack */ - movq 9*8(%rsp), %rdi + /* 8(%rbp) is return addr on stack */ + movq 8(%rbp), %rdi .endif call \func @@ -65,7 +64,7 @@ restore: popq %rdx popq %rsi popq %rdi - FRAME_END + popq %rbp ret _ASM_NOKPROBE(restore) #endif
