| Message ID | 1456276381-30370-1-git-send-email-linus.luessing@c0d3.blue |
|---|---|
| State | Superseded, archived |
| Delegated to: | David Miller |
| Headers | show |
Hi Linus,
[auto build test ERROR on net/master]
[also build test ERROR on v4.5-rc5 next-20160223]
[if your patch is applied to the wrong git tree, please drop us a note to help improving the system]
url: https://github.com/0day-ci/linux/commits/Linus-L-ssing/net-fix-bridge-multicast-packet-checksum-validation/20160224-091615
config: i386-randconfig-x004-201608 (attached as .config)
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
All errors (new ones prefixed by >>):
In file included from include/linux/ip.h:20:0,
from include/net/ip.h:26,
from include/linux/errqueue.h:5,
from net/core/sock.c:96:
>> include/linux/skbuff.h:2826:20: error: redefinition of 'skb_postpush_rcsum'
static inline void skb_postpush_rcsum(struct sk_buff *skb,
^
include/linux/skbuff.h:2796:20: note: previous definition of 'skb_postpush_rcsum' was here
static inline void skb_postpush_rcsum(struct sk_buff *skb,
^
vim +/skb_postpush_rcsum +2826 include/linux/skbuff.h
31b33dfb Pravin B Shelar 2015-09-28 2820 skb_checksum_start_offset(skb) < 0)
6ae459bd Pravin B Shelar 2015-09-22 2821 skb->ip_summed = CHECKSUM_NONE;
^1da177e Linus Torvalds 2005-04-16 2822 }
^1da177e Linus Torvalds 2005-04-16 2823
cbb042f9 Herbert Xu 2006-03-20 2824 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);
cbb042f9 Herbert Xu 2006-03-20 2825
f8ffad69 Daniel Borkmann 2016-01-07 @2826 static inline void skb_postpush_rcsum(struct sk_buff *skb,
f8ffad69 Daniel Borkmann 2016-01-07 2827 const void *start, unsigned int len)
f8ffad69 Daniel Borkmann 2016-01-07 2828 {
f8ffad69 Daniel Borkmann 2016-01-07 2829 /* For performing the reverse operation to skb_postpull_rcsum(),
:::::: The code at line 2826 was first introduced by commit
:::::: f8ffad69c9f8b8dfb0b633425d4ef4d2493ba61a bpf: add skb_postpush_rcsum and fix dev_forward_skb occasions
:::::: TO: Daniel Borkmann <daniel@iogearbox.net>
:::::: CC: David S. Miller <davem@davemloft.net>
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 4ce9ff7..d66e007 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -2784,6 +2784,23 @@ static inline int skb_linearize_cow(struct sk_buff *skb) } /** + * skb_postpush_rcsum - update checksum for received skb after push + * @skb: buffer to update + * @start: start of data before push + * @len: length of data pushed + * + * After doing a push on a received packet, you need to call this to + * update the CHECKSUM_COMPLETE checksum. + */ + +static inline void skb_postpush_rcsum(struct sk_buff *skb, + const void *start, unsigned int len) +{ + if (skb->ip_summed == CHECKSUM_COMPLETE) + skb->csum = csum_add(skb->csum, csum_partial(start, len, 0)); +} + +/** * skb_postpull_rcsum - update checksum for received skb after pull * @skb: buffer to update * @start: start of data before pull diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 5bf88f5..8616d11 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -2948,6 +2948,24 @@ int skb_append_pagefrags(struct sk_buff *skb, struct page *page, EXPORT_SYMBOL_GPL(skb_append_pagefrags); /** + * skb_push_rcsum - push skb and update receive checksum + * @skb: buffer to update + * @len: length of data pulled + * + * This function performs an skb_push on the packet and updates + * the CHECKSUM_COMPLETE checksum. It should be used on + * receive path processing instead of skb_push unless you know + * that the checksum difference is zero (e.g., a valid IP header) + * or you are setting ip_summed to CHECKSUM_NONE. + */ +static unsigned char *skb_push_rcsum(struct sk_buff *skb, unsigned len) +{ + skb_push(skb, len); + skb_postpush_rcsum(skb, skb->data, len); + return skb->data; +} + +/** * skb_pull_rcsum - pull skb and update receive checksum * @skb: buffer to update * @len: length of data pulled @@ -4084,9 +4102,9 @@ struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb, if (!pskb_may_pull(skb_chk, offset)) goto err; - __skb_pull(skb_chk, offset); + skb_pull_rcsum(skb_chk, offset); ret = skb_chkf(skb_chk); - __skb_push(skb_chk, offset); + skb_push_rcsum(skb_chk, offset); if (ret) goto err;
We need to update the skb->csum after pulling the skb, otherwise an unnecessary checksum (re)computation can ocure for IGMP/MLD packets in the bridge code. Additionally this fixes the following splats for network devices / bridge ports with support for and enabled RX checksum offloading: [...] [ 43.986968] eth0: hw csum failure [ 43.990344] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 4.4.0 #2 [ 43.996193] Hardware name: BCM2709 [ 43.999647] [<800204e0>] (unwind_backtrace) from [<8001cf14>] (show_stack+0x10/0x14) [ 44.007432] [<8001cf14>] (show_stack) from [<801ab614>] (dump_stack+0x80/0x90) [ 44.014695] [<801ab614>] (dump_stack) from [<802e4548>] (__skb_checksum_complete+0x6c/0xac) [ 44.023090] [<802e4548>] (__skb_checksum_complete) from [<803a055c>] (ipv6_mc_validate_checksum+0x104/0x178) [ 44.032959] [<803a055c>] (ipv6_mc_validate_checksum) from [<802e111c>] (skb_checksum_trimmed+0x130/0x188) [ 44.042565] [<802e111c>] (skb_checksum_trimmed) from [<803a06e8>] (ipv6_mc_check_mld+0x118/0x338) [ 44.051501] [<803a06e8>] (ipv6_mc_check_mld) from [<803b2c98>] (br_multicast_rcv+0x5dc/0xd00) [ 44.060077] [<803b2c98>] (br_multicast_rcv) from [<803aa510>] (br_handle_frame_finish+0xac/0x51c) [...] Fixes: 9afd85c9e455 ("net: Export IGMP/MLD message validation code") Reported-by: Álvaro Fernández Rojas <noltari@gmail.com> Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue> --- v2: * substituted the storing of the csum with an skb_push_rcsum() approach (did some more reading about CHECKSUM_PARTIAL, and it seems to me that the skb_push direction is actually the easier/"safer" one, so there should be no resetting to CHECKSUM_NONE necessary) * Rewording of commit message, this bug should not cause any packet loss due to "automatic" checksum recomputations in software if skb->csum is bogus (in the CHECKSUM_COMPLETE case) include/linux/skbuff.h | 17 +++++++++++++++++ net/core/skbuff.c | 22 ++++++++++++++++++++-- 2 files changed, 37 insertions(+), 2 deletions(-)