[PATCH] autofs: fix null deref in autofs_fill_super

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[Syz logs]
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 PID: 5098 Comm: syz-executor.0 Not tainted 6.6.0-syzkaller-15601-g4bbdb725a36b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
RIP: 0010:autofs_fill_super+0x47d/0xb50 fs/autofs/inode.c:334

[pid  5095] mount(NULL, "./file1", "autofs", 0, "fd=0x0000000000000000") = -1 ENOMEM (Cannot allocate memory)

[Analysis]
autofs_get_inode() will return null, when memory cannot be allocated.

[Fix]
Confirm that root_inde is not null before using it.

Reported-and-tested-by: syzbot+662f87a8ef490f45fa64@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Edward Adam Davis <eadavis@xxxxxx>
---
 fs/autofs/inode.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/autofs/inode.c b/fs/autofs/inode.c
index a5083d447a62..f2e89a444edf 100644
--- a/fs/autofs/inode.c
+++ b/fs/autofs/inode.c
@@ -331,6 +331,9 @@ static int autofs_fill_super(struct super_block *s, struct fs_context *fc)
 		goto fail;
 
 	root_inode = autofs_get_inode(s, S_IFDIR | 0755);
+	if (!root_inode)
+		goto fail;
+
 	root_inode->i_uid = ctx->uid;
 	root_inode->i_gid = ctx->gid;
 
-- 
2.25.1





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