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authorJeff Layton2023-03-17 13:13:08 -0400
committerGreg Kroah-Hartman2023-03-30 12:49:04 +0200
commit51ddb84baff6f09ad62b5999ece3ec172e4e3568 (patch)
tree5d2de3cad01a79f89c106ad3fb422bba8496f0ac /fs/nfsd
parent1c55982beb80c7d3c30278fc6cfda8496a31dbe6 (diff)
nfsd: don't replace page in rq_pages if it's a continuation of last page
[ Upstream commit 27c934dd8832dd40fd34776f916dc201e18b319b ] The splice read calls nfsd_splice_actor to put the pages containing file data into the svc_rqst->rq_pages array. It's possible however to get a splice result that only has a partial page at the end, if (e.g.) the filesystem hands back a short read that doesn't cover the whole page. nfsd_splice_actor will plop the partial page into its rq_pages array and return. Then later, when nfsd_splice_actor is called again, the remainder of the page may end up being filled out. At this point, nfsd_splice_actor will put the page into the array _again_ corrupting the reply. If this is done enough times, rq_next_page will overrun the array and corrupt the trailing fields -- the rq_respages and rq_next_page pointers themselves. If we've already added the page to the array in the last pass, don't add it to the array a second time when dealing with a splice continuation. This was originally handled properly in nfsd_splice_actor, but commit 91e23b1c3982 ("NFSD: Clean up nfsd_splice_actor()") removed the check for it. Fixes: 91e23b1c3982 ("NFSD: Clean up nfsd_splice_actor()") Cc: Al Viro <viro@zeniv.linux.org.uk> Reported-by: Dario Lesca <d.lesca@solinos.it> Tested-by: David Critch <dcritch@redhat.com> Link: https://bugzilla.redhat.com/show_bug.cgi?id=2150630 Signed-off-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'fs/nfsd')
-rw-r--r--fs/nfsd/vfs.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 59f9a8cee012..dc3ba13546dd 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -874,8 +874,15 @@ nfsd_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
struct page *last_page;
last_page = page + (offset + sd->len - 1) / PAGE_SIZE;
- for (page += offset / PAGE_SIZE; page <= last_page; page++)
+ for (page += offset / PAGE_SIZE; page <= last_page; page++) {
+ /*
+ * Skip page replacement when extending the contents
+ * of the current page.
+ */
+ if (page == *(rqstp->rq_next_page - 1))
+ continue;
svc_rqst_replace_page(rqstp, page);
+ }
if (rqstp->rq_res.page_len == 0) // first call
rqstp->rq_res.page_base = offset % PAGE_SIZE;
rqstp->rq_res.page_len += sd->len;