From 50c73890d314921e2097d47e98c2ca59b3876ec7 Mon Sep 17 00:00:00 2001 From: Mathias Krause Date: Tue, 10 May 2016 23:07:02 +0200 Subject: [PATCH] x86/extable: ensure entries are swapped completely when sorting The x86 exception table sorting was changed in commit 29934b0fb8ff ("x86/extable: use generic search and sort routines") to use the arch independent code in lib/extable.c. However, the patch was mangled somehow on its way into the kernel from the last version posted at [1]. The committed version kind of attempted to incorporate the changes of commit 548acf19234d ("x86/mm: Expand the exception table logic to allow new handling options") as in _completely_ _ignoring_ the x86 specific 'handler' member of struct exception_table_entry. This effectively broke the sorting as entries will only partly be swapped now. Fortunately, the x86 Kconfig selects BUILDTIME_EXTABLE_SORT, so the exception table doesn't need to be sorted at runtime. However, in case that ever changes, we better not break the exception table sorting just because of that. [ Ard Biesheuvel points out that BUILDTIME_EXTABLE_SORT applies to the core image only, but we still rely on the sorting routines for modules in that case - Linus ] Fix this by providing a swap_ex_entry_fixup() macro that takes care of the 'handler' member. [1] https://lkml.org/lkml/2016/1/27/232 Signed-off-by: Mathias Krause Fixes: 29934b0fb8f ("x86/extable: use generic search and sort routines") Reviewed-by: Ard Biesheuvel Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: H. Peter Anvin Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Tony Luck Signed-off-by: Linus Torvalds --- arch/x86/include/asm/uaccess.h | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index a969ae607be8..2e7513d1f1f4 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -108,6 +108,14 @@ struct exception_table_entry { #define ARCH_HAS_RELATIVE_EXTABLE +#define swap_ex_entry_fixup(a, b, tmp, delta) \ + do { \ + (a)->fixup = (b)->fixup + (delta); \ + (b)->fixup = (tmp).fixup - (delta); \ + (a)->handler = (b)->handler + (delta); \ + (b)->handler = (tmp).handler - (delta); \ + } while (0) + extern int fixup_exception(struct pt_regs *regs, int trapnr); extern bool ex_has_fault_handler(unsigned long ip); extern int early_fixup_exception(unsigned long *ip); -- 2.20.1