CVE-2023-53692

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> ext4: fix use-after-free read in ext4_find_extent for bigalloc + inline<br /> <br /> Syzbot found the following issue:<br /> loop0: detected capacity change from 0 to 2048<br /> EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 without journal. Quota mode: none.<br /> ==================================================================<br /> BUG: KASAN: use-after-free in ext4_ext_binsearch_idx fs/ext4/extents.c:768 [inline]<br /> BUG: KASAN: use-after-free in ext4_find_extent+0x76e/0xd90 fs/ext4/extents.c:931<br /> Read of size 4 at addr ffff888073644750 by task syz-executor420/5067<br /> <br /> CPU: 0 PID: 5067 Comm: syz-executor420 Not tainted 6.2.0-rc1-syzkaller #0<br /> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022<br /> Call Trace:<br /> <br /> __dump_stack lib/dump_stack.c:88 [inline]<br /> dump_stack_lvl+0x1b1/0x290 lib/dump_stack.c:106<br /> print_address_description+0x74/0x340 mm/kasan/report.c:306<br /> print_report+0x107/0x1f0 mm/kasan/report.c:417<br /> kasan_report+0xcd/0x100 mm/kasan/report.c:517<br /> ext4_ext_binsearch_idx fs/ext4/extents.c:768 [inline]<br /> ext4_find_extent+0x76e/0xd90 fs/ext4/extents.c:931<br /> ext4_clu_mapped+0x117/0x970 fs/ext4/extents.c:5809<br /> ext4_insert_delayed_block fs/ext4/inode.c:1696 [inline]<br /> ext4_da_map_blocks fs/ext4/inode.c:1806 [inline]<br /> ext4_da_get_block_prep+0x9e8/0x13c0 fs/ext4/inode.c:1870<br /> ext4_block_write_begin+0x6a8/0x2290 fs/ext4/inode.c:1098<br /> ext4_da_write_begin+0x539/0x760 fs/ext4/inode.c:3082<br /> generic_perform_write+0x2e4/0x5e0 mm/filemap.c:3772<br /> ext4_buffered_write_iter+0x122/0x3a0 fs/ext4/file.c:285<br /> ext4_file_write_iter+0x1d0/0x18f0<br /> call_write_iter include/linux/fs.h:2186 [inline]<br /> new_sync_write fs/read_write.c:491 [inline]<br /> vfs_write+0x7dc/0xc50 fs/read_write.c:584<br /> ksys_write+0x177/0x2a0 fs/read_write.c:637<br /> do_syscall_x64 arch/x86/entry/common.c:50 [inline]<br /> do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80<br /> entry_SYSCALL_64_after_hwframe+0x63/0xcd<br /> RIP: 0033:0x7f4b7a9737b9<br /> RSP: 002b:00007ffc5cac3668 EFLAGS: 00000246 ORIG_RAX: 0000000000000001<br /> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f4b7a9737b9<br /> RDX: 00000000175d9003 RSI: 0000000020000200 RDI: 0000000000000004<br /> RBP: 00007f4b7a933050 R08: 0000000000000000 R09: 0000000000000000<br /> R10: 000000000000079f R11: 0000000000000246 R12: 00007f4b7a9330e0<br /> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000<br /> <br /> <br /> Above issue is happens when enable bigalloc and inline data feature. As<br /> commit 131294c35ed6 fixed delayed allocation bug in ext4_clu_mapped for<br /> bigalloc + inline. But it only resolved issue when has inline data, if<br /> inline data has been converted to extent(ext4_da_convert_inline_data_to_extent)<br /> before writepages, there is no EXT4_STATE_MAY_INLINE_DATA flag. However<br /> i_data is still store inline data in this scene. Then will trigger UAF<br /> when find extent.<br /> To resolve above issue, there is need to add judge "ext4_has_inline_data(inode)"<br /> in ext4_clu_mapped().