From 6ccc9e1128e50e518ecdf9e1b120c735e40de25a Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Wed, 16 Jan 2019 10:27:59 +0100 Subject: fuse: handle zero sized retrieve correctly commit 97e1532ef81acb31c30f9e75bf00306c33a77812 upstream. Dereferencing req->page_descs[0] will Oops if req->max_pages is zero. Reported-by: syzbot+c1e36d30ee3416289cc0@syzkaller.appspotmail.com Tested-by: syzbot+c1e36d30ee3416289cc0@syzkaller.appspotmail.com Fixes: b2430d7567a3 ("fuse: add per-page descriptor to fuse_req") Cc: # v3.9 Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman --- fs/fuse/dev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index c5e38061a48b..baaed4d05b22 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -1698,7 +1698,6 @@ static int fuse_retrieve(struct fuse_conn *fc, struct inode *inode, req->in.h.nodeid = outarg->nodeid; req->in.numargs = 2; req->in.argpages = 1; - req->page_descs[0].offset = offset; req->end = fuse_retrieve_end; index = outarg->offset >> PAGE_SHIFT; @@ -1713,6 +1712,7 @@ static int fuse_retrieve(struct fuse_conn *fc, struct inode *inode, this_num = min_t(unsigned, num, PAGE_SIZE - offset); req->pages[req->num_pages] = page; + req->page_descs[req->num_pages].offset = offset; req->page_descs[req->num_pages].length = this_num; req->num_pages++; -- cgit v1.2.3