Ubuntu: (Multiple Advisories) (CVE-2024-42305): Linux kernel vulnerabilities
Description
In the Linux kernel, the following vulnerability has been resolved: ext4: check dot and dotdot of dx_root before making dir indexed Syzbot reports a issue as follows: ============================================ BUG: unable to handle page fault for address: ffffed11022e24fe PGD 23ffee067 P4D 23ffee067 PUD 0 Oops: Oops: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 0 PID: 5079 Comm: syz-executor306 Not tainted 6.10.0-rc5-g55027e689933 #0 Call Trace: <TASK> make_indexed_dir+0xdaf/0x13c0 fs/ext4/namei.c:2341 ext4_add_entry+0x222a/0x25d0 fs/ext4/namei.c:2451 ext4_rename fs/ext4/namei.c:3936 [inline] ext4_rename2+0x26e5/0x4370 fs/ext4/namei.c:4214 [...] ============================================ The immediate cause of this problem is that there is only one valid dentry for the block to be split during do_split, so split==0 results in out of bounds accesses to the map triggering the issue. do_split unsigned split dx_make_map count = 1 split = count/2 = 0; continued = hash2 == map[split - 1].hash; ---> map[4294967295] The maximum length of a filename is 255 and the minimum block size is 1024, so it is always guaranteed that the number of entries is greater than or equal to 2 when do_split() is called. But syzbot's crafted image has no dot and dotdot in dir, and the dentry distribution in dirblock is as follows: bus dentry1 hole dentry2 free |xx--|xx-------------|...............|xx-------------|...............| 0 12 (8+248)=256 268 256 524 (8+256)=264 788 236 1024 So when renaming dentry1 increases its name_len length by 1, neither hole nor free is sufficient to hold the new dentry, and make_indexed_dir() is called. In make_indexed_dir() it is assumed that the first two entries of the dirblock must be dot and dotdot, so bus and dentry1 are left in dx_root because they are treated as dot and dotdot, and only dentry2 is moved to the new leaf block. That's why count is equal to 1. Therefore add the ext4_check_dx_root() helper function to add more sanity checks to dot and dotdot before starting the conversion to avoid the above issue.
Solution(s)
- ubuntu-upgrade-linux-image-5-15-0-1038-xilinx-zynqmp
- ubuntu-upgrade-linux-image-5-15-0-1055-gkeop
- ubuntu-upgrade-linux-image-5-15-0-1065-ibm
- ubuntu-upgrade-linux-image-5-15-0-1065-raspi
- ubuntu-upgrade-linux-image-5-15-0-1067-nvidia
- ubuntu-upgrade-linux-image-5-15-0-1067-nvidia-lowlatency
- ubuntu-upgrade-linux-image-5-15-0-1069-gke
- ubuntu-upgrade-linux-image-5-15-0-1069-kvm
- ubuntu-upgrade-linux-image-5-15-0-1070-oracle
- ubuntu-upgrade-linux-image-5-15-0-1071-gcp
- ubuntu-upgrade-linux-image-5-15-0-1072-aws
- ubuntu-upgrade-linux-image-5-15-0-1075-azure
- ubuntu-upgrade-linux-image-5-15-0-125-generic
- ubuntu-upgrade-linux-image-5-15-0-125-generic-64k
- ubuntu-upgrade-linux-image-5-15-0-125-generic-lpae
- ubuntu-upgrade-linux-image-5-15-0-125-lowlatency
- ubuntu-upgrade-linux-image-5-15-0-125-lowlatency-64k
- ubuntu-upgrade-linux-image-5-4-0-1044-iot
- ubuntu-upgrade-linux-image-5-4-0-1054-xilinx-zynqmp
- ubuntu-upgrade-linux-image-5-4-0-1082-ibm
- ubuntu-upgrade-linux-image-5-4-0-1094-bluefield
- ubuntu-upgrade-linux-image-5-4-0-1102-gkeop
- ubuntu-upgrade-linux-image-5-4-0-1119-raspi
- ubuntu-upgrade-linux-image-5-4-0-1123-kvm
- ubuntu-upgrade-linux-image-5-4-0-1134-oracle
- ubuntu-upgrade-linux-image-5-4-0-1135-aws
- ubuntu-upgrade-linux-image-5-4-0-1139-azure
- ubuntu-upgrade-linux-image-5-4-0-1139-gcp
- ubuntu-upgrade-linux-image-5-4-0-1140-azure
- ubuntu-upgrade-linux-image-5-4-0-200-generic
- ubuntu-upgrade-linux-image-5-4-0-200-generic-lpae
- ubuntu-upgrade-linux-image-5-4-0-200-lowlatency
- ubuntu-upgrade-linux-image-aws
- ubuntu-upgrade-linux-image-aws-lts-20-04
- ubuntu-upgrade-linux-image-aws-lts-22-04
- ubuntu-upgrade-linux-image-azure
- ubuntu-upgrade-linux-image-azure-lts-20-04
- ubuntu-upgrade-linux-image-azure-lts-22-04
- ubuntu-upgrade-linux-image-bluefield
- ubuntu-upgrade-linux-image-gcp
- ubuntu-upgrade-linux-image-gcp-lts-20-04
- ubuntu-upgrade-linux-image-gcp-lts-22-04
- ubuntu-upgrade-linux-image-generic
- ubuntu-upgrade-linux-image-generic-64k
- ubuntu-upgrade-linux-image-generic-64k-hwe-20-04
- ubuntu-upgrade-linux-image-generic-hwe-18-04
- ubuntu-upgrade-linux-image-generic-hwe-20-04
- ubuntu-upgrade-linux-image-generic-lpae
- ubuntu-upgrade-linux-image-generic-lpae-hwe-20-04
- ubuntu-upgrade-linux-image-gke
- ubuntu-upgrade-linux-image-gke-5-15
- ubuntu-upgrade-linux-image-gkeop
- ubuntu-upgrade-linux-image-gkeop-5-15
- ubuntu-upgrade-linux-image-gkeop-5-4
- ubuntu-upgrade-linux-image-ibm
- ubuntu-upgrade-linux-image-ibm-lts-20-04
- ubuntu-upgrade-linux-image-kvm
- ubuntu-upgrade-linux-image-lowlatency
- ubuntu-upgrade-linux-image-lowlatency-64k
- ubuntu-upgrade-linux-image-lowlatency-64k-hwe-20-04
- ubuntu-upgrade-linux-image-lowlatency-hwe-18-04
- ubuntu-upgrade-linux-image-lowlatency-hwe-20-04
- ubuntu-upgrade-linux-image-nvidia
- ubuntu-upgrade-linux-image-nvidia-lowlatency
- ubuntu-upgrade-linux-image-oem
- ubuntu-upgrade-linux-image-oem-20-04
- ubuntu-upgrade-linux-image-oem-20-04b
- ubuntu-upgrade-linux-image-oem-20-04c
- ubuntu-upgrade-linux-image-oem-20-04d
- ubuntu-upgrade-linux-image-oem-osp1
- ubuntu-upgrade-linux-image-oracle
- ubuntu-upgrade-linux-image-oracle-lts-20-04
- ubuntu-upgrade-linux-image-oracle-lts-22-04
- ubuntu-upgrade-linux-image-raspi
- ubuntu-upgrade-linux-image-raspi-hwe-18-04
- ubuntu-upgrade-linux-image-raspi-nolpae
- ubuntu-upgrade-linux-image-raspi2
- ubuntu-upgrade-linux-image-snapdragon-hwe-18-04
- ubuntu-upgrade-linux-image-virtual
- ubuntu-upgrade-linux-image-virtual-hwe-18-04
- ubuntu-upgrade-linux-image-virtual-hwe-20-04
- ubuntu-upgrade-linux-image-xilinx-zynqmp
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