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authorStuart MENEFY <stuart.menefy@st.com>2008-10-10 19:49:30 +0100
committerPaul Mundt <lethal@linux-sh.org>2008-11-13 17:40:30 +0900
commit5d52013cbb3d39bde9f5a6023193058eeb112e98 (patch)
treee941d9e884132d72c002536955014a938d740906
parent2cd0ebc83d771220eeddec91fd6d4cfefc2cc46e (diff)
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 <dylan_reid@bose.com> Signed-off-by: Stuart Menefy <stuart.menefy@st.com> Signed-off-by: Paul Mundt <lethal@linux-sh.org>
-rw-r--r--arch/sh/lib/copy_page.S11
1 files 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