diff options
| author | Alban Crequy <albancrequy@linux.microsoft.com> | 2022-11-10 09:56:13 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-11-25 17:45:53 +0100 |
| commit | db744288af730abb66312f40b087d1dbf794c5f4 (patch) | |
| tree | 1a81b74f83afef8986a02cd85c293c41b1e71eb4 /mm | |
| parent | 24cc679abbf31477d0cc6106ec83c2fbae6b3cdf (diff) | |
maccess: Fix writing offset in case of fault in strncpy_from_kernel_nofault()
commit 8678ea06852cd1f819b870c773d43df888d15d46 upstream.
If a page fault occurs while copying the first byte, this function resets one
byte before dst.
As a consequence, an address could be modified and leaded to kernel crashes if
case the modified address was accessed later.
Fixes: b58294ead14c ("maccess: allow architectures to provide kernel probing directly")
Signed-off-by: Alban Crequy <albancrequy@linux.microsoft.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Tested-by: Francis Laniel <flaniel@linux.microsoft.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: <stable@vger.kernel.org> [5.8]
Link: https://lore.kernel.org/bpf/20221110085614.111213-2-albancrequy@linux.microsoft.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/maccess.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/maccess.c b/mm/maccess.c index 3bd70405f2d8..f6ea117a69eb 100644 --- a/mm/maccess.c +++ b/mm/maccess.c @@ -83,7 +83,7 @@ long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count) return src - unsafe_addr; Efault: pagefault_enable(); - dst[-1] = '\0'; + dst[0] = '\0'; return -EFAULT; } #else /* HAVE_GET_KERNEL_NOFAULT */ |