From 5d52013cbb3d39bde9f5a6023193058eeb112e98 Mon Sep 17 00:00:00 2001 From: Stuart MENEFY Date: Fri, 10 Oct 2008 19:49:30 +0100 Subject: [PATCH] sh: __copy_user function can corrupt the stack in case of exception The __copy_user function can corrupt the stack in the case of a non-trivial length of data, and either of the first two move instructions cause an exception. This is because the fixup for these two instructions is mapped to the no_pop case, but these instructions execute after the stack is pushed. This change creates an explicit NO_POP exception mapping macro, and uses it for the two instructions executed in the trivial case where no stack pushes occur. More information at ST Linux bugzilla: https://bugzilla.stlinux.com/show_bug.cgi?id=4824 Signed-off-by: Dylan Reid Signed-off-by: Stuart Menefy Signed-off-by: Paul Mundt --- arch/sh/lib/copy_page.S | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/arch/sh/lib/copy_page.S b/arch/sh/lib/copy_page.S index 5d12e657be3..43de7e8e4e1 100644 --- a/arch/sh/lib/copy_page.S +++ b/arch/sh/lib/copy_page.S @@ -80,6 +80,11 @@ ENTRY(copy_page) .section __ex_table, "a"; \ .long 9999b, 6000f ; \ .previous +#define EX_NO_POP(...) \ + 9999: __VA_ARGS__ ; \ + .section __ex_table, "a"; \ + .long 9999b, 6005f ; \ + .previous ENTRY(__copy_user) ! Check if small number of bytes mov #11,r0 @@ -139,9 +144,9 @@ EX( mov.b r1,@r4 ) bt 1f 2: -EX( mov.b @r5+,r0 ) +EX_NO_POP( mov.b @r5+,r0 ) dt r6 -EX( mov.b r0,@r4 ) +EX_NO_POP( mov.b r0,@r4 ) bf/s 2b add #1,r4 @@ -150,7 +155,7 @@ EX( mov.b r0,@r4 ) # Exception handler: .section .fixup, "ax" -6000: +6005: mov.l 8000f,r1 mov r3,r0 jmp @r1 -- 2.41.0