Affected: Alpaquita:stream: linux-lts

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

ext4: allow ext4_get_group_info() to fail

Previously, ext4_get_group_info() would treat an invalid group number as BUG(), since in theory it should never happen. However, if a malicious attaker (or fuzzer) modifies the superblock via the block device while it is the file system is mounted, it is possible for s_first_data_block to get set to a very large number. In that case, when calculating the block group of some block number (such as the starting block of a preallocation region), could result in an underflow and very large block group number. Then the BUG_ON check in ext4_get_group_info() would fire, resutling in a denial of service attack that can be triggered by root or someone with write access to the block device.

For a quality of implementation perspective, it's best that even if the system administrator does something that they shouldn't, that it will not trigger a BUG. So instead of BUG'ing, ext4_get_group_info() will call ext4_error and return NULL. We also add fallback code in all of the callers of ext4_get_group_info() that it might NULL.

Also, since ext4_get_group_info() was already borderline to be an inline function, un-inline it. The results in a next reduction of the compiled text size of ext4 by roughly 2k.

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

ext4: allow ext4_get_group_info() to fail

Previously, ext4_get_group_info() would treat an invalid group number as BUG(), since in theory it should never happen. However, if a malicious attaker (or fuzzer) modifies the superblock via the block device while it is the file system is mounted, it is possible for s_first_data_block to get set to a very large number. In that case, when calculating the block group of some block number (such as the starting block of a preallocation region), could result in an underflow and very large block group number. Then the BUG_ON check in ext4_get_group_info() would fire, resutling in a denial of service attack that can be triggered by root or someone with write access to the block device.

For a quality of implementation perspective, it's best that even if the system administrator does something that they shouldn't, that it will not trigger a BUG. So instead of BUG'ing, ext4_get_group_info() will call ext4_error and return NULL. We also add fallback code in all of the callers of ext4_get_group_info() that it might NULL.

Also, since ext4_get_group_info() was already borderline to be an inline function, un-inline it. The results in a next reduction of the compiled text size of ext4 by roughly 2k.

kernel: vt_ioctl: fix array_index_nospec in vt_setactivate kernel: pstore/ram: Fix crash when setting number of cpus to an odd number kernel: PM / devfreq: Synchronize devfreq_monitor_[start/stop] kernel: net/smc: avoid data corruption caused by decline kernel: scsi: ibmvfc: Remove BUG_ON in the case of an empty event pool kernel: ext4: allow ext4_get_group_info() to fail kernel: ext4: correct grp validation in ext4_mb_good_group kernel: ext4: regenerate buddy after block freeing failed if under fc replay kernel: net/smc: fix illegal rmb_desc access in SMC-D connection dump kernel: fs/proc: do_task_stat: use sig->stats_lock to gather the threads/children stats kernel: ext4: fix double-free of blocks due to wrong extents moved_len kernel: Bluetooth: l2cap: fix null-ptr-deref in l2cap_chan_timeout kernel: s390/qeth: Fix kernel panic after setting hsuid kernel: drm/vmwgfx: Fix invalid reads in fence signaled events kernel: blk-cgroup: fix list corruption from reorder of WRITE ->lqueued kernel: of: module: add buffer overflow check in of_modalias() kernel: net/mlx5: Discard command completions in internal error kernel: net: hns3: fix kernel crash problem in concurrent scenario kernel: cpufreq: amd-pstate: fix memory leak on CPU EPP exit kernel: tcp: avoid too many retransmit packets kernel: drm/amdgpu: change vm->task_info handling kernel: bpf: Fix overrunning reservations in ringbuf kernel: mm/filemap: skip to create PMD-sized page cache if needed kernel: firmware: cs_dsp…

Affected: Ubuntu:Pro:14.04:LTS: linux, Ubuntu:Pro:14.04:LTS: linux-aws, Ubuntu:Pro:14.04:LTS: linux-azure, Ubuntu:Pro:14.04:LTS: linux-lts-xenial, Ubuntu:Pro:16.04:LTS: linux, Ubuntu:Pro:16.04:LTS: linux-aws, Ubuntu:Pro:16.04:LTS: linux-aws-hwe, Ubuntu:Pro:16.04:LTS: linux-azure, Ubuntu:Pro:16.04:LTS: linux-gcp, Ubuntu:Pro:16.04:LTS: linux-hwe and 163 more

In the Linux kernel, the following vulnerability has been resolved: ext4: allow ext4_get_group_info() to fail Previously, ext4_get_group_info() would treat an invalid group number as BUG(), since in theory it should never happen. However, if a malicious attaker (or fuzzer) modifies the superblock via the block device while it is the file system is mounted, it is possible for s_first_data_block to get set to a very large number. In that case, when calculating the block group of some block number (such as the starting block of a preallocation region), could result in an underflow and very large block group number. Then the BUG_ON check in ext4_get_group_info() would fire, resutling in a denial of service attack that can be triggered by root or someone with write access to the block device. For a quality of implementation perspective, it's best that even if the system administrator does something that they shouldn't, that it will not trigger a BUG. So instead of BUG'ing, ext4_get_group_info() will call ext4_error and return NULL. We also add fallback code in all of the callers of ext4_get_group_info() that it might NULL. Also, since ext4_get_group_info() was already borderline to be an inline function, un-inline it. The results in a next reduction of the compiled text size of ext4 by roughly 2k.

Ein Angreifer kann mehrere Schwachstellen im Linux Kernel ausnutzen, um einen Denial of Service Angriff durchzuführen und um nicht nähere beschriebene Effekte zu verursachen.