Affected: Alpaquita:stream: linux-lts

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

mm/MADV_COLLAPSE: catch !none !huge !bad pmd lookups

In commit 34488399fa08 ("mm/madvise: add file and shmem support to MADV_COLLAPSE") we make the following change to find_pmd_or_thp_or_none():

- if (!pmd_present(pmde)) - return SCAN_PMD_NULL; + if (pmd_none(pmde)) + return SCAN_PMD_NONE;

This was for-use by MADV_COLLAPSE file/shmem codepaths, where MADV_COLLAPSE might identify a pte-mapped hugepage, only to have khugepaged race-in, free the pte table, and clear the pmd. Such codepaths include:

A) If we find a suitably-aligned compound page of order HPAGE_PMD_ORDER already in the pagecache. B) In retract_page_tables(), if we fail to grab mmap_lock for the target mm/address.

In these cases, collapse_pte_mapped_thp() really does expect a none (not just !present) pmd, and we want to suitably identify that case separate from the case where no pmd is found, or it's a bad-pmd (of course, many things could happen once we drop mmap_lock, and the pmd could plausibly undergo multiple transitions due to intervening fault, split, etc). Regardless, the code is prepared install a huge-pmd only when the existing pmd entry is either a genuine pte-table-mapping-pmd, or the none-pmd.

However, the commit introduces a logical hole; namely, that we've allowed !none- && !huge- && !bad-pmds to be classified as genuine pte-table-mapping-pmds. One such example that could l…

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

mm/MADV_COLLAPSE: catch !none !huge !bad pmd lookups

In commit 34488399fa08 ("mm/madvise: add file and shmem support to MADV_COLLAPSE") we make the following change to find_pmd_or_thp_or_none():

- if (!pmd_present(pmde)) - return SCAN_PMD_NULL; + if (pmd_none(pmde)) + return SCAN_PMD_NONE;

This was for-use by MADV_COLLAPSE file/shmem codepaths, where MADV_COLLAPSE might identify a pte-mapped hugepage, only to have khugepaged race-in, free the pte table, and clear the pmd. Such codepaths include:

A) If we find a suitably-aligned compound page of order HPAGE_PMD_ORDER already in the pagecache. B) In retract_page_tables(), if we fail to grab mmap_lock for the target mm/address.

In these cases, collapse_pte_mapped_thp() really does expect a none (not just !present) pmd, and we want to suitably identify that case separate from the case where no pmd is found, or it's a bad-pmd (of course, many things could happen once we drop mmap_lock, and the pmd could plausibly undergo multiple transitions due to intervening fault, split, etc). Regardless, the code is prepared install a huge-pmd only when the existing pmd entry is either a genuine pte-table-mapping-pmd, or the none-pmd.

However, the commit introduces a logical hole; namely, that we've allowed !none- && !huge- && !bad-pmds to be classified as genuine pte-table-mapping-pmds. One such example that could l…

kernel: Bluetooth BR/EDR PIN Pairing procedure is vulnerable to an impersonation attack kernel: ovl: fix warning in ovl_create_real() kernel: memcg does not limit the number of POSIX file locks allowing memory exhaustion kernel: vmwgfx: NULL pointer dereference in vmw_cmd_dx_define_query kernel: integer overflow in l2cap_config_req() in net/bluetooth/l2cap_core.c kernel: i2c: mlxbf: prevent stack overflow in mlxbf_i2c_smbus_start_transaction() kernel: Bluetooth: L2CAP: Fix u8 overflow kernel: hwmon: (coretemp) fix pci device refcount leak in nv1a_ram_new() kernel: tracing: Fix sleeping function called from invalid context on RT kernel kernel: net: mdio: unexport __init-annotated mdio_bus_init() kernel: arm64: ftrace: consistently handle PLTs. kernel: mm/uffd: fix pte marker when fork() without fork event kernel: Bluetooth: Fix a buffer overflow in mgmt_mesh_add() kernel: tty: n_gsm: add sanity check for gsm->receive in gsm_receive_buf() kernel: ftrace: Fix NULL pointer dereference in is_ftrace_trampoline when ftrace is dead kernel: tee: add overflow check in register_shm_helper() kernel: tty: n_gsm: fix deadlock and link starvation in outgoing data path kernel: PM: hibernate: defer device probing when resuming from hibernation kernel: ext4: don't allow journal inode to have encrypt flag kernel: ext4: fix delayed allocation bug in ext4_clu_mapped for bigalloc + inline kernel: erofs: fix order >= MAX_ORDER warning due to crafted negative i_size kernel: perf/x86/intel/uncore: F…

Affected: Ubuntu:16.04:LTS: linux-hwe-edge, Ubuntu:18.04:LTS: linux-aws-5.0, Ubuntu:18.04:LTS: linux-aws-5.3, Ubuntu:18.04:LTS: linux-azure, Ubuntu:18.04:LTS: linux-azure-5.3, Ubuntu:18.04:LTS: linux-azure-edge, Ubuntu:18.04:LTS: linux-gcp, Ubuntu:18.04:LTS: linux-gcp-5.3, Ubuntu:18.04:LTS: linux-gke-4.15, Ubuntu:18.04:LTS: linux-gke-5.4 and 70 more

In the Linux kernel, the following vulnerability has been resolved: mm/MADV_COLLAPSE: catch !none !huge !bad pmd lookups In commit 34488399fa08 ("mm/madvise: add file and shmem support to MADV_COLLAPSE") we make the following change to find_pmd_or_thp_or_none(): - if (!pmd_present(pmde)) - return SCAN_PMD_NULL; + if (pmd_none(pmde)) + return SCAN_PMD_NONE; This was for-use by MADV_COLLAPSE file/shmem codepaths, where MADV_COLLAPSE might identify a pte-mapped hugepage, only to have khugepaged race-in, free the pte table, and clear the pmd. Such codepaths include: A) If we find a suitably-aligned compound page of order HPAGE_PMD_ORDER already in the pagecache. B) In retract_page_tables(), if we fail to grab mmap_lock for the target mm/address. In these cases, collapse_pte_mapped_thp() really does expect a none (not just !present) pmd, and we want to suitably identify that case separate from the case where no pmd is found, or it's a bad-pmd (of course, many things could happen once we drop mmap_lock, and the pmd could plausibly undergo multiple transitions due to intervening fault, split, etc). Regardless, the code is prepared install a huge-pmd only when the existing pmd entry is either a genuine pte-table-mapping-pmd, or the none-pmd. However, the commit introduces a logical hole; namely, that we've allowed !none- && !huge- && !bad-pmds to be classified as genuine pte-table-mapping-pmds. One such example that could leak thro…

Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Linux Kernel ausnutzen, um einen Denial of Service Angriff durchzuführen oder nicht spezifizierte Effekte zu erzielen.