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| author | Stuart MENEFY <stuart.menefy@st.com> | 2008-10-10 19:49:30 +0100 |
|---|---|---|
| committer | Paul Mundt <lethal@linux-sh.org> | 2008-11-13 17:40:30 +0900 |
| commit | 5d52013cbb3d39bde9f5a6023193058eeb112e98 (patch) | |
| tree | e941d9e884132d72c002536955014a938d740906 /arch/sh | |
| parent | 2cd0ebc83d771220eeddec91fd6d4cfefc2cc46e (diff) | |
| download | lwn-5d52013cbb3d39bde9f5a6023193058eeb112e98.tar.gz lwn-5d52013cbb3d39bde9f5a6023193058eeb112e98.zip | |
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>
Diffstat (limited to 'arch/sh')
| -rw-r--r-- | arch/sh/lib/copy_page.S | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/arch/sh/lib/copy_page.S b/arch/sh/lib/copy_page.S index 5d12e657be34..43de7e8e4e17 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 |