From 48faa7ca4de5ce7270c86ab041ab35f25d4587b2 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Wed, 22 Jan 2014 23:04:33 -0500 Subject: [PATCH] alpha: fix broken network checksum 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 Signed-off-by: Matt Turner --- arch/alpha/lib/csum_partial_copy.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/alpha/lib/csum_partial_copy.c b/arch/alpha/lib/csum_partial_copy.c index ff3c10721caf6..5675dca8dbb14 100644 --- a/arch/alpha/lib/csum_partial_copy.c +++ b/arch/alpha/lib/csum_partial_copy.c @@ -378,6 +378,11 @@ csum_partial_copy_from_user(const void __user *src, void *dst, int len, __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; } -- 2.39.5