CVE-2022-49349

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> ext4: fix use-after-free in ext4_rename_dir_prepare<br /> <br /> We got issue as follows:<br /> EXT4-fs (loop0): mounted filesystem without journal. Opts: ,errors=continue<br /> ext4_get_first_dir_block: bh-&gt;b_data=0xffff88810bee6000 len=34478<br /> ext4_get_first_dir_block: *parent_de=0xffff88810beee6ae bh-&gt;b_data=0xffff88810bee6000<br /> ext4_rename_dir_prepare: [1] parent_de=0xffff88810beee6ae<br /> ==================================================================<br /> BUG: KASAN: use-after-free in ext4_rename_dir_prepare+0x152/0x220<br /> Read of size 4 at addr ffff88810beee6ae by task rep/1895<br /> <br /> CPU: 13 PID: 1895 Comm: rep Not tainted 5.10.0+ #241<br /> Call Trace:<br /> dump_stack+0xbe/0xf9<br /> print_address_description.constprop.0+0x1e/0x220<br /> kasan_report.cold+0x37/0x7f<br /> ext4_rename_dir_prepare+0x152/0x220<br /> ext4_rename+0xf44/0x1ad0<br /> ext4_rename2+0x11c/0x170<br /> vfs_rename+0xa84/0x1440<br /> do_renameat2+0x683/0x8f0<br /> __x64_sys_renameat+0x53/0x60<br /> do_syscall_64+0x33/0x40<br /> entry_SYSCALL_64_after_hwframe+0x44/0xa9<br /> RIP: 0033:0x7f45a6fc41c9<br /> RSP: 002b:00007ffc5a470218 EFLAGS: 00000246 ORIG_RAX: 0000000000000108<br /> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f45a6fc41c9<br /> RDX: 0000000000000005 RSI: 0000000020000180 RDI: 0000000000000005<br /> RBP: 00007ffc5a470240 R08: 00007ffc5a470160 R09: 0000000020000080<br /> R10: 00000000200001c0 R11: 0000000000000246 R12: 0000000000400bb0<br /> R13: 00007ffc5a470320 R14: 0000000000000000 R15: 0000000000000000<br /> <br /> The buggy address belongs to the page:<br /> page:00000000440015ce refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x10beee<br /> flags: 0x200000000000000()<br /> raw: 0200000000000000 ffffea00043ff4c8 ffffea0004325608 0000000000000000<br /> raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000<br /> page dumped because: kasan: bad access detected<br /> <br /> Memory state around the buggy address:<br /> ffff88810beee580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff<br /> ffff88810beee600: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff<br /> &gt;ffff88810beee680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff<br /> ^<br /> ffff88810beee700: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff<br /> ffff88810beee780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff<br /> ==================================================================<br /> Disabling lock debugging due to kernel taint<br /> ext4_rename_dir_prepare: [2] parent_de-&gt;inode=3537895424<br /> ext4_rename_dir_prepare: [3] dir=0xffff888124170140<br /> ext4_rename_dir_prepare: [4] ino=2<br /> ext4_rename_dir_prepare: ent-&gt;dir-&gt;i_ino=2 parent=-757071872<br /> <br /> Reason is first directory entry which &amp;#39;rec_len&amp;#39; is 34478, then will get illegal<br /> parent entry. Now, we do not check directory entry after read directory block<br /> in &amp;#39;ext4_get_first_dir_block&amp;#39;.<br /> To solve this issue, check directory entry in &amp;#39;ext4_get_first_dir_block&amp;#39;.<br /> <br /> [ Trigger an ext4_error() instead of just warning if the directory is<br /> missing a &amp;#39;.&amp;#39; or &amp;#39;..&amp;#39; entry. Also make sure we return an error code<br /> if the file system is corrupted. -TYT ]