[34-longterm 111/196] ARM: 6891/1: prevent heap corruption in OABI semtimedop

[Paul Gortmaker]

From: Dan Rosenberg <drosenberg@xxxxxxxxxxxxx>

                   -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    If you see a problem with using this for longterm, please comment.
                   -------------------

commit 0f22072ab50cac7983f9660d33974b45184da4f9 upstream.

When CONFIG_OABI_COMPAT is set, the wrapper for semtimedop does not
bound the nsops argument.  A sufficiently large value will cause an
integer overflow in allocation size, followed by copying too much data
into the allocated buffer.  Fix this by restricting nsops to SEMOPM.
Untested.

Signed-off-by: Dan Rosenberg <drosenberg@xxxxxxxxxxxxx>
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
 arch/arm/kernel/sys_oabi-compat.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/kernel/sys_oabi-compat.c b/arch/arm/kernel/sys_oabi-compat.c
index 33ff678..73bb15c 100644
--- a/arch/arm/kernel/sys_oabi-compat.c
+++ b/arch/arm/kernel/sys_oabi-compat.c
@@ -311,7 +311,7 @@ asmlinkage long sys_oabi_semtimedop(int semid,
 	long err;
 	int i;
 
-	if (nsops < 1)
+	if (nsops < 1 || nsops > SEMOPM)
 		return -EINVAL;
 	sops = kmalloc(sizeof(*sops) * nsops, GFP_KERNEL);
 	if (!sops)
-- 
1.7.9.3

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