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MIPS: uaccess: Fix strlen_user with EVA

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The strlen_user() function calls __strlen_kernel_asm in both branches of
the eva_kernel_access() conditional. For EVA it should be calling
__strlen_user_eva for user accesses, otherwise it will load from the
kernel address space instead of the user address space, and the access
checking will likely be ineffective at preventing it due to EVA's
overlapping user and kernel address spaces.

This was found after extending the test_user_copy module to cover user
string access functions, which gave the following error with EVA:

test_user_copy: illegal strlen_user passed

Fortunately the use of strlen_user() has been all but eradicated from
the mainline kernel, so only out of tree modules could be affected.

Fixes: e3a9b07a9c ("MIPS: asm: uaccess: Add EVA support for str*_user operations")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Leonid Yegoshin <leonid.yegoshin@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: <stable@vger.kernel.org> # 3.15.x-
Patchwork: https://patchwork.linux-mips.org/patch/10842/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
James Hogan 2015-08-05 16:41:37 +01:00 committed by Ralf Baechle
parent 4ef7675344
commit 5dc62fdd83
1 changed files with 1 additions and 1 deletions
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2
arch/mips/include/asm/uaccess.h
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@ -1384,7 +1384,7 @@ static inline long strlen_user(const char __user *s)
might_fault();
__asm__ __volatile__(
"move\t$4, %1\n\t"
__MODULE_JAL(__strlen_kernel_asm)
__MODULE_JAL(__strlen_user_asm)
"move\t%0, $2"
: "=r" (res)
: "r" (s)