Commit 0ef38d70 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Matt Turner

alpha: fix broken network checksum

The patch 3ddc5b46 breaks networking on
alpha (there is a follow-up fix 5cfe8f1b,
but networking is still broken even with the second patch).

The patch 3ddc5b46 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: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarMatt Turner <mattst88@gmail.com>
parent a9302e84
...@@ -378,6 +378,11 @@ csum_partial_copy_from_user(const void __user *src, void *dst, int len, ...@@ -378,6 +378,11 @@ csum_partial_copy_from_user(const void __user *src, void *dst, int len,
__wsum __wsum
csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum) csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
{ {
return csum_partial_copy_from_user((__force const void __user *)src, __wsum checksum;
dst, len, sum, NULL); 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;
} }
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