[PATCH] jfs: fix array-index-out-of-bounds in jfs_readdir

[PATCH] jfs: fix array-index-out-of-bounds in jfs_readdir

[Ghanshyam Agrawal]

The stbl might contain some invalid values. Added a check to
return error code in that case.

Reported-by: syzbot+0315f8fe99120601ba88@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=0315f8fe99120601ba88
Signed-off-by: Ghanshyam Agrawal <ghanshyam1898@gmail.com>
---
 fs/jfs/jfs_dtree.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/fs/jfs/jfs_dtree.c b/fs/jfs/jfs_dtree.c
index 5d3127ca68a4..c8f6e51ac047 100644
--- a/fs/jfs/jfs_dtree.c
+++ b/fs/jfs/jfs_dtree.c
@@ -2891,6 +2891,14 @@ int jfs_readdir(struct file *file, struct dir_context *ctx)
 		stbl = DT_GETSTBL(p);
 
 		for (i = index; i < p->header.nextindex; i++) {
+			if (stbl[i] < 0 || stbl[i] > 127) {
+				DT_PUTPAGE(mp);
+				free_page(dirent_buf);
+				jfs_err("JFS: Invalid stbl[%d] = %d for inode %ld, block = %lld",
+				i, stbl[i], (long)ip->i_ino, (long long)bn);
+				return -EIO;
+			}
+
 			d = (struct ldtentry *) & p->slot[stbl[i]];
 
 			if (((long) jfs_dirent + d->namlen + 1) >
-- 
2.34.1

Re: [PATCH] jfs: fix array-index-out-of-bounds in jfs_readdir

[Dave Kleikamp]

On 10/1/24 1:05AM, Ghanshyam Agrawal wrote:
> The stbl might contain some invalid values. Added a check to
> return error code in that case.
> 
> Reported-by: syzbot+0315f8fe99120601ba88@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=0315f8fe99120601ba88
> Signed-off-by: Ghanshyam Agrawal <ghanshyam1898@gmail.com>
> ---
>   fs/jfs/jfs_dtree.c | 8 ++++++++
>   1 file changed, 8 insertions(+)
> 
> diff --git a/fs/jfs/jfs_dtree.c b/fs/jfs/jfs_dtree.c
> index 5d3127ca68a4..c8f6e51ac047 100644
> --- a/fs/jfs/jfs_dtree.c
> +++ b/fs/jfs/jfs_dtree.c
> @@ -2891,6 +2891,14 @@ int jfs_readdir(struct file *file, struct dir_context *ctx)
>   		stbl = DT_GETSTBL(p);
>   
>   		for (i = index; i < p->header.nextindex; i++) {
> +			if (stbl[i] < 0 || stbl[i] > 127) {
> +				DT_PUTPAGE(mp);
> +				free_page(dirent_buf);
> +				jfs_err("JFS: Invalid stbl[%d] = %d for inode %ld, block = %lld",
> +				i, stbl[i], (long)ip->i_ino, (long long)bn);

I'm moving the printing of the error message before the call to 
DT_PUTPAGE() since stbl is part of the page's data. And I'm fixing the 
indent.

> +				return -EIO;
> +			}
> +
>   			d = (struct ldtentry *) & p->slot[stbl[i]];
>   
>   			if (((long) jfs_dirent + d->namlen + 1) >

Otherwise, looks good. I'll be applying this one.

Shaggy