[PATCH] jfs : fix shift-out-of-bounds in dbUpdatePMap

[PATCH] jfs : fix shift-out-of-bounds in dbUpdatePMap

[Manas Ghandat]

Currently there is no bound check for number of logical blocks per
page (bmp->db_l2nbperpage). Added the required bound check for the
calculation of dmap.

Reported-by: syzbot+91ad2b52815a08caf4ea@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=91ad2b52815a08caf4ea
Fixes: 4d81715fc5df ("[PATCH] fs/jfs: Conversion to generic boolean")
Signed-off-by: Manas Ghandat <ghandatmanas@gmail.com>
---
 fs/jfs/jfs_dmap.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
index a3eb1e826947..6a5df296fdc8 100644
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -467,6 +467,10 @@ dbUpdatePMap(struct inode *ipbmap,
 	lastlblkno = 0;
 	for (rem = nblocks; rem > 0; rem -= nblks, blkno += nblks) {
 		/* get the buffer for the current dmap. */
+
+		if (bmp->db_l2nbperpage > L2BPERDMAP)
+			return -EIO;
+
 		lblkno = BLKTODMAP(blkno, bmp->db_l2nbperpage);
 		if (lblkno != lastlblkno) {
 			if (mp) {
-- 
2.37.2

Re: [PATCH] jfs : fix shift-out-of-bounds in dbUpdatePMap

[Dave Kleikamp]

On 8/27/23 12:05AM, Manas Ghandat wrote:
> Currently there is no bound check for number of logical blocks per
> page (bmp->db_l2nbperpage). Added the required bound check for the
> calculation of dmap.

This should already be fixed by 11509910c599 ("jfs: jfs_dmap: Validate 
db_l2nbperpage while mounting")

Can you please verify if this problem still exists in v6.5?

Shaggy

> 
> Reported-by: syzbot+91ad2b52815a08caf4ea@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=91ad2b52815a08caf4ea
> Fixes: 4d81715fc5df ("[PATCH] fs/jfs: Conversion to generic boolean")
> Signed-off-by: Manas Ghandat <ghandatmanas@gmail.com>
> ---
>   fs/jfs/jfs_dmap.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
> index a3eb1e826947..6a5df296fdc8 100644
> --- a/fs/jfs/jfs_dmap.c
> +++ b/fs/jfs/jfs_dmap.c
> @@ -467,6 +467,10 @@ dbUpdatePMap(struct inode *ipbmap,
>   	lastlblkno = 0;
>   	for (rem = nblocks; rem > 0; rem -= nblks, blkno += nblks) {
>   		/* get the buffer for the current dmap. */
> +
> +		if (bmp->db_l2nbperpage > L2BPERDMAP)
> +			return -EIO;
> +
>   		lblkno = BLKTODMAP(blkno, bmp->db_l2nbperpage);
>   		if (lblkno != lastlblkno) {
>   			if (mp) {

Re: [PATCH] jfs : fix shift-out-of-bounds in dbUpdatePMap

[Manas Ghandat]

I checked for the v6.5. Its fixed there.

On 29/08/23 23:19, Dave Kleikamp wrote:
> On 8/27/23 12:05AM, Manas Ghandat wrote:
>> Currently there is no bound check for number of logical blocks per
>> page (bmp->db_l2nbperpage). Added the required bound check for the
>> calculation of dmap.
>
> This should already be fixed by 11509910c599 ("jfs: jfs_dmap: Validate 
> db_l2nbperpage while mounting")
>
> Can you please verify if this problem still exists in v6.5?
>
> Shaggy
>

Re: [PATCH] jfs : fix shift-out-of-bounds in dbUpdatePMap

[Dave Kleikamp]

Thanks for verifying!

On 8/30/23 11:58AM, Manas Ghandat wrote:
> I checked for the v6.5. Its fixed there.
> 
> On 29/08/23 23:19, Dave Kleikamp wrote:
>> On 8/27/23 12:05AM, Manas Ghandat wrote:
>>> Currently there is no bound check for number of logical blocks per
>>> page (bmp->db_l2nbperpage). Added the required bound check for the
>>> calculation of dmap.
>>
>> This should already be fixed by 11509910c599 ("jfs: jfs_dmap: Validate 
>> db_l2nbperpage while mounting")
>>
>> Can you please verify if this problem still exists in v6.5?
>>
>> Shaggy
>>