From: Willem de Bruijn <willemb@xxxxxxxxxx> commit 52cbd23a119c6ebf40a527e53f3402d2ea38eccb upstream. When iteratively computing a checksum with csum_block_add, track the offset "pos" to correctly rotate in csum_block_add when offset is odd. The open coded implementation of skb_copy_and_csum_datagram did this. With the switch to __skb_datagram_iter calling csum_and_copy_to_iter, pos was reinitialized to 0 on each call. Bring back the pos by passing it along with the csum to the callback. Changes v1->v2 - pass csum value, instead of csump pointer (Alexander Duyck) Link: https://lore.kernel.org/netdev/20210128152353.GB27281@optiplex/ Fixes: 950fcaecd5cc ("datagram: consolidate datagram copy to iter helpers") Reported-by: Oliver Graute <oliver.graute@xxxxxxxxx> Signed-off-by: Willem de Bruijn <willemb@xxxxxxxxxx> Reviewed-by: Alexander Duyck <alexanderduyck@xxxxxx> Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx> Link: https://lore.kernel.org/r/20210203192952.1849843-1-willemdebruijn.kernel@xxxxxxxxx Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- include/linux/uio.h | 8 +++++++- lib/iov_iter.c | 24 ++++++++++++++---------- net/core/datagram.c | 12 ++++++++++-- 3 files changed, 31 insertions(+), 13 deletions(-) --- a/include/linux/uio.h +++ b/include/linux/uio.h @@ -260,7 +260,13 @@ static inline void iov_iter_reexpand(str { i->count = count; } -size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csump, struct iov_iter *i); + +struct csum_state { + __wsum csum; + size_t off; +}; + +size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csstate, struct iov_iter *i); size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i); bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i); size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp, --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -592,14 +592,15 @@ static __wsum csum_and_memcpy(void *to, } static size_t csum_and_copy_to_pipe_iter(const void *addr, size_t bytes, - __wsum *csum, struct iov_iter *i) + struct csum_state *csstate, + struct iov_iter *i) { struct pipe_inode_info *pipe = i->pipe; unsigned int p_mask = pipe->ring_size - 1; + __wsum sum = csstate->csum; + size_t off = csstate->off; unsigned int i_head; size_t n, r; - size_t off = 0; - __wsum sum = *csum; if (!sanity(i)) return 0; @@ -621,7 +622,8 @@ static size_t csum_and_copy_to_pipe_iter i_head++; } while (n); i->count -= bytes; - *csum = sum; + csstate->csum = sum; + csstate->off = off; return bytes; } @@ -1522,18 +1524,19 @@ bool csum_and_copy_from_iter_full(void * } EXPORT_SYMBOL(csum_and_copy_from_iter_full); -size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csump, +size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *_csstate, struct iov_iter *i) { + struct csum_state *csstate = _csstate; const char *from = addr; - __wsum *csum = csump; __wsum sum, next; - size_t off = 0; + size_t off; if (unlikely(iov_iter_is_pipe(i))) - return csum_and_copy_to_pipe_iter(addr, bytes, csum, i); + return csum_and_copy_to_pipe_iter(addr, bytes, _csstate, i); - sum = *csum; + sum = csstate->csum; + off = csstate->off; if (unlikely(iov_iter_is_discard(i))) { WARN_ON(1); /* for now */ return 0; @@ -1561,7 +1564,8 @@ size_t csum_and_copy_to_iter(const void off += v.iov_len; }) ) - *csum = sum; + csstate->csum = sum; + csstate->off = off; return bytes; } EXPORT_SYMBOL(csum_and_copy_to_iter); --- a/net/core/datagram.c +++ b/net/core/datagram.c @@ -721,8 +721,16 @@ static int skb_copy_and_csum_datagram(co struct iov_iter *to, int len, __wsum *csump) { - return __skb_datagram_iter(skb, offset, to, len, true, - csum_and_copy_to_iter, csump); + struct csum_state csdata = { .csum = *csump }; + int ret; + + ret = __skb_datagram_iter(skb, offset, to, len, true, + csum_and_copy_to_iter, &csdata); + if (ret) + return ret; + + *csump = csdata.csum; + return 0; } /**
