From: David Howells dhowells@redhat.com
[ Upstream commit 1199db603511d7463d9d3840f96f61967affc766 ]
Fix the total-length calculation in afs_make_call() when the operation being dispatched has data from a series of pages attached.
Despite the patched code looking like that it should reduce mathematically to the current code, it doesn't because the 32-bit unsigned arithmetic being used to calculate the page-offset-difference doesn't correctly extend to a 64-bit value when the result is effectively negative.
Without this, some FS.StoreData operations that span multiple pages fail, reporting too little or too much data.
Signed-off-by: David Howells dhowells@redhat.com Signed-off-by: Sasha Levin alexander.levin@verizon.com --- fs/afs/rxrpc.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/fs/afs/rxrpc.c b/fs/afs/rxrpc.c index 0bf191f0dbaf..9f715c3edcf9 100644 --- a/fs/afs/rxrpc.c +++ b/fs/afs/rxrpc.c @@ -377,8 +377,17 @@ int afs_make_call(struct in_addr *addr, struct afs_call *call, gfp_t gfp, */ tx_total_len = call->request_size; if (call->send_pages) { - tx_total_len += call->last_to - call->first_offset; - tx_total_len += (call->last - call->first) * PAGE_SIZE; + if (call->last == call->first) { + tx_total_len += call->last_to - call->first_offset; + } else { + /* It looks mathematically like you should be able to + * combine the following lines with the ones above, but + * unsigned arithmetic is fun when it wraps... + */ + tx_total_len += PAGE_SIZE - call->first_offset; + tx_total_len += call->last_to; + tx_total_len += (call->last - call->first - 1) * PAGE_SIZE; + } }
/* create a call */