On 2024/11/26 1:56, Leo Stone wrote:
On Mon, Nov 25, 2024 at 07:16:41PM +0800, Chao Yu wrote:

I'm fine w/ this change, but I didn't get it, how did above commit introduce
this bug?

Hello Chao,

The commit from the bisect didn't exactly introduce this bug, since it
would still be possible to make a different image that does the exact
same thing in the older code.

This commit was blamed in the bisect because it changes the layout of
struct f2fs_inode:

@@ -271,6 +272,10 @@ struct f2fs_inode {
                        __le32 i_inode_checksum;/* inode meta checksum */
                        __le64 i_crtime;        /* creation time */
                        __le32 i_crtime_nsec;   /* creation time in nano scale 
*/
+                       __le64 i_compr_blocks;  /* # of compressed blocks */
+                       __u8 i_compress_algorithm;      /* compress algorithm */
+                       __u8 i_log_cluster_size;        /* log of cluster size 
*/
+                       __le16 i_padding;               /* padding */
                        __le32 i_extra_end[0];  /* for attribute size 
calculation */
                } __packed;
                __le32 i_addr[DEF_ADDRS_PER_INODE];     /* Pointers to data 
blocks */

This changes F2FS_TOTAL_EXTRA_ATTR_SIZE, which allows the syzbot
reproducer's inode to pass the sanity check for corrupted i_extra_size.
Before this change, the inode gets rejected as corrupt:

[   62.794566][ T9662] F2FS-fs (loop0): sanity_check_inode: inode (ino=7) has 
corrupted i_extra_isize: 36, max: 24

Leo,

Ah, right, thanks for the explanation, anyway, can you please correct this
"Fixes line"?

Thanks,


Thanks,
Leo



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