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Message-ID: <tencent_E4796C489550EB0EEEEACD6C797A6F1C2E0A@qq.com>
From: Edward Adam Davis <eadavis@qq.com>
To: syzbot+d2125fcb6aa8c4276fd2@syzkaller.appspotmail.com
Cc: linux-kernel@vger.kernel.org,
	syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [fs?] general protection fault in iter_file_splice_write
Date: Wed, 22 May 2024 21:29:57 +0800
In-Reply-To: <0000000000002fd2de0618de2e65@google.com>
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please test null ptr in iter_file_splice_write

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 33e02dc69afb

diff --git a/fs/splice.c b/fs/splice.c
index 60aed8de21f8..cf5d417b5f66 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -751,9 +751,15 @@ iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
 
 		/* dismiss the fully eaten buffers, adjust the partial one */
 		tail = pipe->tail;
-		while (ret) {
+		n = 0;
+		while (ret > 0 && n < nbufs) {
 			struct pipe_buffer *buf = &pipe->bufs[tail & mask];
-			if (ret >= buf->len) {
+			printk("ret: %ld, nbufs: %d,  buf len: %lu, n: %d, %s\n", ret, nbufs, buf->len, n,  __func__);
+			if (!buf->len) {
+				tail++;
+				continue;
+			}
+			if (ret >= (ssize_t)buf->len) {
 				ret -= buf->len;
 				buf->len = 0;
 				pipe_buf_release(pipe, buf);
@@ -766,6 +772,7 @@ iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
 				buf->len -= ret;
 				ret = 0;
 			}
+			n++;
 		}
 	}
 done: