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SubjectRe: [PATCH] fs: jfs: fix shift-out-of-bounds in dbAllocAG
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On 10/8/22 9:00PM, Dongliang Mu wrote:
> On Thu, Sep 29, 2022 at 1:47 PM Dongliang Mu <dzm91@hust.edu.cn> wrote:
>>
>> From: Dongliang Mu <mudongliangabcd@gmail.com>
>>
>> Syzbot found a crash : UBSAN: shift-out-of-bounds in dbAllocAG. The
>> underlying bug is the missing check of bmp->db_agl2size. The field can
>> be greater than 32 and trigger the shift-out-of-bounds.
>>
>> Fix this bug by adding a check of bmp->db_agl2size in dbMount since this
>> field is used in many following functions. Note that, for maintainance,
>> I reorganzie the error handling code of dbMount.
>>
>> Reported-by: syzbot+15342c1aa6a00fb7a438@syzkaller.appspotmail.com
>> Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
>> ---
>> fs/jfs/jfs_dmap.c | 21 +++++++++++++++------
>> 1 file changed, 15 insertions(+), 6 deletions(-)
>>
>> diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
>> index 6b838d3ae7c2..4c717f245920 100644
>> --- a/fs/jfs/jfs_dmap.c
>> +++ b/fs/jfs/jfs_dmap.c
>> @@ -155,7 +155,7 @@ int dbMount(struct inode *ipbmap)
>> struct bmap *bmp;
>> struct dbmap_disk *dbmp_le;
>> struct metapage *mp;
>> - int i;
>> + int i, err;
>>
>> /*
>> * allocate/initialize the in-memory bmap descriptor
>> @@ -170,8 +170,8 @@ int dbMount(struct inode *ipbmap)
>> BMAPBLKNO << JFS_SBI(ipbmap->i_sb)->l2nbperpage,
>> PSIZE, 0);
>> if (mp == NULL) {
>> - kfree(bmp);
>> - return -EIO;
>> + err = -EIO;
>> + goto err_kfree_bmp;
>> }
>>
>> /* copy the on-disk bmap descriptor to its in-memory version. */
>> @@ -181,9 +181,8 @@ int dbMount(struct inode *ipbmap)
>> bmp->db_l2nbperpage = le32_to_cpu(dbmp_le->dn_l2nbperpage);
>> bmp->db_numag = le32_to_cpu(dbmp_le->dn_numag);
>> if (!bmp->db_numag) {
>> - release_metapage(mp);
>> - kfree(bmp);
>> - return -EINVAL;
>> + err = -EINVAL;
>> + goto err_release_metapage;
>> }
>>
>> bmp->db_maxlevel = le32_to_cpu(dbmp_le->dn_maxlevel);
>> @@ -194,6 +193,10 @@ int dbMount(struct inode *ipbmap)
>> bmp->db_agwidth = le32_to_cpu(dbmp_le->dn_agwidth);
>> bmp->db_agstart = le32_to_cpu(dbmp_le->dn_agstart);
>> bmp->db_agl2size = le32_to_cpu(dbmp_le->dn_agl2size);
>> + if (bmp->db_agl2size >= 32) {
>> + err = -EINVAL;
>> + goto err_release_metapage;
>> + }
>> for (i = 0; i < MAXAG; i++)
>> bmp->db_agfree[i] = le64_to_cpu(dbmp_le->dn_agfree[i]);
>> bmp->db_agsize = le64_to_cpu(dbmp_le->dn_agsize);
>> @@ -214,6 +217,12 @@ int dbMount(struct inode *ipbmap)
>> BMAP_LOCK_INIT(bmp);
>>
>> return (0);
>> +
>> +err_release_metapage:
>> + release_metapage(mp);
>> +err_kfree_bmp:
>> + kfree(bmp);
>> + return err;
>> }
>>
>
> ping?

Sorry, it's taking me so long to get to this. It looks good, but I'll
give it a little better look and push it.

Shaggy

>
>>
>> --
>> 2.35.1
>>

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