In the Linux kernel, the following vulnerability has been resolved:

ext4: fix use-after-free in ext4orphancleanup

I caught a issue as follows:

BUG: KASAN: use-after-free in __listaddvalid+0x28/0x1a0 Read of size 8 at addr ffff88814b13f378 by task mount/710

CPU: 1 PID: 710 Comm: mount Not tainted 6.1.0-rc3-next #370 Call Trace: <TASK> dumpstacklvl+0x73/0x9f printreport+0x25d/0x759 kasanreport+0xc0/0x120 __asan_load8+0x99/0x140 __listaddvalid+0x28/0x1a0 ext4orphancleanup+0x564/0x9d0 [ext4] __ext4fillsuper+0x48e2/0x5300 [ext4] ext4fillsuper+0x19f/0x3a0 [ext4] gettreebdev+0x27b/0x450 ext4gettree+0x19/0x30 [ext4] vfsgettree+0x49/0x150 pathmount+0xaae/0x1350 domount+0xe2/0x110 __x64sysmount+0xf0/0x190 dosyscall64+0x35/0x80 entrySYSCALL64afterhwframe+0x63/0xcd </TASK>

[...]

Above issue may happen as follows:

ext4fillsuper ext4orphancleanup --- loop1: assume lastorphan is 12 --- listadd(&EXT4I(inode)->iorphan, &EXT4SB(sb)->sorphan) ext4truncate --> return 0 ext4inodeattachjinode --> return -ENOMEM iput(inode) --> free inode<12> --- loop2: lastorphan is still 12 --- listadd(&EXT4I(inode)->iorphan, &EXT4SB(sb)->sorphan); // use inode<12> and trigger UAF

To solve this issue, we need to propagate the return value of ext4inodeattach_jinode() appropriately.