The patch
3d61501b649b7fc975cf496eec73ba5c28f9fb76 breaks networking on
alpha (there is a follow-up fix
62c41b3384d10048e974ee040a9723d4d6b6ba5e,
but networking is still broken even with the second patch).
The patch
3d61501b649b7fc975cf496eec73ba5c28f9fb76 makes
csum_partial_copy_from_user check the pointer with access_ok. However,
csum_partial_copy_from_user is called also from csum_partial_copy_nocheck
and csum_partial_copy_nocheck is called on kernel pointers and it is
supposed not to check pointer validity.
This bug results in ssh session hangs if the system is loaded and bulk
data are printed to ssh terminal.
This patch fixes csum_partial_copy_nocheck to call set_fs(KERNEL_DS), so
that access_ok in csum_partial_copy_from_user accepts kernel-space
addresses.
Cc: stable@vger.kernel.org
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Matt Turner <mattst88@gmail.com>
__wsum
csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
{
- return csum_partial_copy_from_user((__force const void __user *)src,
- dst, len, sum, NULL);
+ __wsum checksum;
+ mm_segment_t oldfs = get_fs();
+ set_fs(KERNEL_DS);
+ checksum = csum_partial_copy_from_user((__force const void __user *)src,
+ dst, len, sum, NULL);
+ set_fs(oldfs);
+ return checksum;
}