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| author | James Hogan <james.hogan@imgtec.com> | 2017-05-02 21:41:06 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-05-25 16:44:46 +0300 |
| commit | e8a8a6972c5075e6057264c45614d13f9e0307e5 (patch) | |
| tree | 39b99fdc2331c3dab1ef829d9ac47a73710c67de /arch | |
| parent | 9fefcb947ec2c2b6900b4c10aface329af0fd9c5 (diff) | |
| download | linux-e8a8a6972c5075e6057264c45614d13f9e0307e5.tar.xz | |
metag/uaccess: Check access_ok in strncpy_from_user
commit 3a158a62da0673db918b53ac1440845a5b64fd90 upstream.
The metag implementation of strncpy_from_user() doesn't validate the src
pointer, which could allow reading of arbitrary kernel memory. Add a
short access_ok() check to prevent that.
Its still possible for it to read across the user/kernel boundary, but
it will invariably reach a NUL character after only 9 bytes, leaking
only a static kernel address being loaded into D0Re0 at the beginning of
__start, which is acceptable for the immediate fix.
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: linux-metag@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/metag/include/asm/uaccess.h | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/arch/metag/include/asm/uaccess.h b/arch/metag/include/asm/uaccess.h index ed6cd90ec5ca..3db381205928 100644 --- a/arch/metag/include/asm/uaccess.h +++ b/arch/metag/include/asm/uaccess.h @@ -194,8 +194,13 @@ do { \ extern long __must_check __strncpy_from_user(char *dst, const char __user *src, long count); -#define strncpy_from_user(dst, src, count) __strncpy_from_user(dst, src, count) - +static inline long +strncpy_from_user(char *dst, const char __user *src, long count) +{ + if (!access_ok(VERIFY_READ, src, 1)) + return -EFAULT; + return __strncpy_from_user(dst, src, count); +} /* * Return the size of a string (including the ending 0) * |