CVSS: -EPSS: 0%CPEs: 2EXPL: 0CVE-2024-38306 – btrfs: protect folio::private when attaching extent buffer folios
https://notcve.org/view.php?id=CVE-2024-38306
In the Linux kernel, the following vulnerability has been resolved: btrfs: protect folio::private when attaching extent buffer folios [BUG] Since v6.8 there are rare kernel crashes reported by various people, the common factor is bad page status error messages like this: BUG: Bad page state in process kswapd0 pfn:d6e840 page: refcount:0 mapcount:0 mapping:000000007512f4f2 index:0x2796c2c7c pfn:0xd6e840 aops:btree_aops ino:1 flags: 0x17ffffe0000008(uptodate|node=0|zone=2|lastcpupid=0x3fffff) page_type: 0xffffffff() raw: 0017ffffe0000008 dead000000000100 dead000000000122 ffff88826d0be4c0 raw: 00000002796c2c7c 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: non-NULL mapping [CAUSE] Commit 09e6cef19c9f ("btrfs: refactor alloc_extent_buffer() to allocate-then-attach method") changes the sequence when allocating a new extent buffer. Previously we always called grab_extent_buffer() under mapping->i_private_lock, to ensure the safety on modification on folio::private (which is a pointer to extent buffer for regular sectorsize). This can lead to the following race: Thread A is trying to allocate an extent buffer at bytenr X, with 4 4K pages, meanwhile thread B is trying to release the page at X + 4K (the second page of the extent buffer at X). Thread A | Thread B -----------------------------------+------------------------------------- | btree_release_folio() | | This is for the page at X + 4K, | | Not page X. | | alloc_extent_buffer() | |- release_extent_buffer() |- filemap_add_folio() for the | | |- atomic_dec_and_test(eb->refs) | page at bytenr X (the first | | | | page). | | | | Which returned -EEXIST. | | | | | | | |- filemap_lock_folio() | | | | Returned the first page locked. | | | | | | | |- grab_extent_buffer() | | | | |- atomic_inc_not_zero() | | | | | Returned false | | | | |- folio_detach_private() | | |- folio_detach_private() for X | |- folio_test_private() | | |- folio_test_private() | Returned true | | | Returned true |- folio_put() | |- folio_put() Now there are two puts on the same folio at folio X, leading to refcount underflow of the folio X, and eventually causing the BUG_ON() on the page->mapping. The condition is not that easy to hit: - The release must be triggered for the middle page of an eb If the release is on the same first page of an eb, page lock would kick in and prevent the race. - folio_detach_private() has a very small race window It's only between folio_test_private() and folio_clear_private(). That's exactly when mapping->i_private_lock is used to prevent such race, and commit 09e6cef19c9f ("btrfs: refactor alloc_extent_buffer() to allocate-then-attach method") screwed that up. At that time, I thought the page lock would kick in as filemap_release_folio() also requires the page to be locked, but forgot the filemap_release_folio() only locks one page, not all pages of an extent buffer. [FIX] Move all the code requiring i_private_lock into attach_eb_folio_to_filemap(), so that everything is done with proper lock protection. Furthermore to prevent future problems, add an extra lockdep_assert_locked() to ensure we're holding the proper lock. To reproducer that is able to hit the race (takes a few minutes with instrumented code inserting delays to alloc_extent_buffer()): #! • https://git.kernel.org/stable/c/09e6cef19c9fc0e10547135476865b5272aa0406 https://git.kernel.org/stable/c/952f048eb901881a7cc6f7c1368b53cd386ead7b https://git.kernel.org/stable/c/f3a5367c679d31473d3fbb391675055b4792c309 •
CVSS: -EPSS: 0%CPEs: 4EXPL: 0CVE-2024-37354 – btrfs: fix crash on racing fsync and size-extending write into prealloc
https://notcve.org/view.php?id=CVE-2024-37354
In the Linux kernel, the following vulnerability has been resolved: btrfs: fix crash on racing fsync and size-extending write into prealloc We have been seeing crashes on duplicate keys in btrfs_set_item_key_safe(): BTRFS critical (device vdb): slot 4 key (450 108 8192) new key (450 108 8192) ------------[ cut here ]------------ kernel BUG at fs/btrfs/ctree.c:2620! invalid opcode: 0000 [#1] PREEMPT SMP PTI CPU: 0 PID: 3139 Comm: xfs_io Kdump: loaded Not tainted 6.9.0 #6 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-2.fc40 04/01/2014 RIP: 0010:btrfs_set_item_key_safe+0x11f/0x290 [btrfs] With the following stack trace: #0 btrfs_set_item_key_safe (fs/btrfs/ctree.c:2620:4) #1 btrfs_drop_extents (fs/btrfs/file.c:411:4) #2 log_one_extent (fs/btrfs/tree-log.c:4732:9) #3 btrfs_log_changed_extents (fs/btrfs/tree-log.c:4955:9) #4 btrfs_log_inode (fs/btrfs/tree-log.c:6626:9) #5 btrfs_log_inode_parent (fs/btrfs/tree-log.c:7070:8) #6 btrfs_log_dentry_safe (fs/btrfs/tree-log.c:7171:8) #7 btrfs_sync_file (fs/btrfs/file.c:1933:8) #8 vfs_fsync_range (fs/sync.c:188:9) #9 vfs_fsync (fs/sync.c:202:9) #10 do_fsync (fs/sync.c:212:9) #11 __do_sys_fdatasync (fs/sync.c:225:9) #12 __se_sys_fdatasync (fs/sync.c:223:1) #13 __x64_sys_fdatasync (fs/sync.c:223:1) #14 do_syscall_x64 (arch/x86/entry/common.c:52:14) #15 do_syscall_64 (arch/x86/entry/common.c:83:7) #16 entry_SYSCALL_64+0xaf/0x14c (arch/x86/entry/entry_64.S:121) So we're logging a changed extent from fsync, which is splitting an extent in the log tree. But this split part already exists in the tree, triggering the BUG(). This is the state of the log tree at the time of the crash, dumped with drgn (https://github.com/osandov/drgn/blob/main/contrib/btrfs_tree.py) to get more details than btrfs_print_leaf() gives us: >>> print_extent_buffer(prog.crashed_thread().stack_trace()[0]["eb"]) leaf 33439744 level 0 items 72 generation 9 owner 18446744073709551610 leaf 33439744 flags 0x100000000000000 fs uuid e5bd3946-400c-4223-8923-190ef1f18677 chunk uuid d58cb17e-6d02-494a-829a-18b7d8a399da item 0 key (450 INODE_ITEM 0) itemoff 16123 itemsize 160 generation 7 transid 9 size 8192 nbytes 8473563889606862198 block group 0 mode 100600 links 1 uid 0 gid 0 rdev 0 sequence 204 flags 0x10(PREALLOC) atime 1716417703.220000000 (2024-05-22 15:41:43) ctime 1716417704.983333333 (2024-05-22 15:41:44) mtime 1716417704.983333333 (2024-05-22 15:41:44) otime 17592186044416.000000000 (559444-03-08 01:40:16) item 1 key (450 INODE_REF 256) itemoff 16110 itemsize 13 index 195 namelen 3 name: 193 item 2 key (450 XATTR_ITEM 1640047104) itemoff 16073 itemsize 37 location key (0 UNKNOWN.0 0) type XATTR transid 7 data_len 1 name_len 6 name: user.a data a item 3 key (450 EXTENT_DATA 0) itemoff 16020 itemsize 53 generation 9 type 1 (regular) extent data disk byte 303144960 nr 12288 extent data offset 0 nr 4096 ram 12288 extent compression 0 (none) item 4 key (450 EXTENT_DATA 4096) itemoff 15967 itemsize 53 generation 9 type 2 (prealloc) prealloc data disk byte 303144960 nr 12288 prealloc data offset 4096 nr 8192 item 5 key (450 EXTENT_DATA 8192) itemoff 15914 itemsize 53 generation 9 type 2 (prealloc) prealloc data disk byte 303144960 nr 12288 prealloc data offset 8192 nr 4096 ... So the real problem happened earlier: notice that items 4 (4k-12k) and 5 (8k-12k) overlap. Both are prealloc extents. Item 4 straddles i_size and item 5 starts at i_size. Here is the state of ---truncated--- • https://git.kernel.org/stable/c/1ff2bd566fbcefcb892be85c493bdb92b911c428 https://git.kernel.org/stable/c/3d08c52ba1887a1ff9c179d4b6a18b427bcb2097 https://git.kernel.org/stable/c/f4e5ed974876c14d3623e04dc43d3e3281bc6011 https://git.kernel.org/stable/c/9d274c19a71b3a276949933859610721a453946b •
CVSS: -EPSS: 0%CPEs: 8EXPL: 0CVE-2024-37078 – nilfs2: fix potential kernel bug due to lack of writeback flag waiting
https://notcve.org/view.php?id=CVE-2024-37078
In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix potential kernel bug due to lack of writeback flag waiting Destructive writes to a block device on which nilfs2 is mounted can cause a kernel bug in the folio/page writeback start routine or writeback end routine (__folio_start_writeback in the log below): kernel BUG at mm/page-writeback.c:3070! Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI ... RIP: 0010:__folio_start_writeback+0xbaa/0x10e0 Code: 25 ff 0f 00 00 0f 84 18 01 00 00 e8 40 ca c6 ff e9 17 f6 ff ff e8 36 ca c6 ff 4c 89 f7 48 c7 c6 80 c0 12 84 e8 e7 b3 0f 00 90 <0f> 0b e8 1f ca c6 ff 4c 89 f7 48 c7 c6 a0 c6 12 84 e8 d0 b3 0f 00 ... Call Trace: <TASK> nilfs_segctor_do_construct+0x4654/0x69d0 [nilfs2] nilfs_segctor_construct+0x181/0x6b0 [nilfs2] nilfs_segctor_thread+0x548/0x11c0 [nilfs2] kthread+0x2f0/0x390 ret_from_fork+0x4b/0x80 ret_from_fork_asm+0x1a/0x30 </TASK> This is because when the log writer starts a writeback for segment summary blocks or a super root block that use the backing device's page cache, it does not wait for the ongoing folio/page writeback, resulting in an inconsistent writeback state. Fix this issue by waiting for ongoing writebacks when putting folios/pages on the backing device into writeback state. • https://git.kernel.org/stable/c/9ff05123e3bfbb1d2b68ba1d9bf1f7d1dffc1453 https://git.kernel.org/stable/c/95f6f81e50d858a7c9aa7c795ec14a0ac3819118 https://git.kernel.org/stable/c/a75b8f493dfc48aa38c518430bd9e03b53bffebe https://git.kernel.org/stable/c/0ecfe3a92869a59668d27228dabbd7965e83567f https://git.kernel.org/stable/c/33900d7eae616647e179eee1c66ebe654ee39627 https://git.kernel.org/stable/c/271dcd977ccda8c7a26e360425ae7b4db7d2ecc0 https://git.kernel.org/stable/c/614d397be0cf43412b3f94a0f6460eddced8ce92 https://git.kernel.org/stable/c/1f3bff69f1214fe03a02bc650d5bbfaa6 •
CVSS: -EPSS: 0%CPEs: 7EXPL: 0CVE-2022-48772 – media: lgdt3306a: Add a check against null-pointer-def
https://notcve.org/view.php?id=CVE-2022-48772
In the Linux kernel, the following vulnerability has been resolved: media: lgdt3306a: Add a check against null-pointer-def The driver should check whether the client provides the platform_data. The following log reveals it: [ 29.610324] BUG: KASAN: null-ptr-deref in kmemdup+0x30/0x40 [ 29.610730] Read of size 40 at addr 0000000000000000 by task bash/414 [ 29.612820] Call Trace: [ 29.613030] <TASK> [ 29.613201] dump_stack_lvl+0x56/0x6f [ 29.613496] ? kmemdup+0x30/0x40 [ 29.613754] print_report.cold+0x494/0x6b7 [ 29.614082] ? kmemdup+0x30/0x40 [ 29.614340] kasan_report+0x8a/0x190 [ 29.614628] ? kmemdup+0x30/0x40 [ 29.614888] kasan_check_range+0x14d/0x1d0 [ 29.615213] memcpy+0x20/0x60 [ 29.615454] kmemdup+0x30/0x40 [ 29.615700] lgdt3306a_probe+0x52/0x310 [ 29.616339] i2c_device_probe+0x951/0xa90 • https://git.kernel.org/stable/c/8915dcd29a82096acacf54364a8425363782aea0 https://git.kernel.org/stable/c/b479fd59a1f4a342b69fce34f222d93bf791dca4 https://git.kernel.org/stable/c/526238d32c3acc3d597fd8c9a34652bfe9086cea https://git.kernel.org/stable/c/d082757b8359201c3864323cea4b91ea30a1e676 https://git.kernel.org/stable/c/7d12e918f2994c883f41f22552a61b9310fa1e87 https://git.kernel.org/stable/c/8e1e00718d0d9dd83337300572561e30b9c0d115 https://git.kernel.org/stable/c/c1115ddbda9c930fba0fdd062e7a8873ebaf898d •
CVSS: 8.8EPSS: 0%CPEs: 1EXPL: 0CVE-2021-4440 – x86/xen: Drop USERGS_SYSRET64 paravirt call
https://notcve.org/view.php?id=CVE-2021-4440
In the Linux kernel, the following vulnerability has been resolved: x86/xen: Drop USERGS_SYSRET64 paravirt call commit afd30525a659ac0ae0904f0cb4a2ca75522c3123 upstream. USERGS_SYSRET64 is used to return from a syscall via SYSRET, but a Xen PV guest will nevertheless use the IRET hypercall, as there is no sysret PV hypercall defined. So instead of testing all the prerequisites for doing a sysret and then mangling the stack for Xen PV again for doing an iret just use the iret exit from the beginning. This can easily be done via an ALTERNATIVE like it is done for the sysenter compat case already. It should be noted that this drops the optimization in Xen for not restoring a few registers when returning to user mode, but it seems as if the saved instructions in the kernel more than compensate for this drop (a kernel build in a Xen PV guest was slightly faster with this patch applied). While at it remove the stale sysret32 remnants. [ pawan: Brad Spengler and Salvatore Bonaccorso <carnil@debian.org> reported a problem with the 5.10 backport commit edc702b4a820 ("x86/entry_64: Add VERW just before userspace transition"). When CONFIG_PARAVIRT_XXL=y, CLEAR_CPU_BUFFERS is not executed in syscall_return_via_sysret path as USERGS_SYSRET64 is runtime patched to: .cpu_usergs_sysret64 = { 0x0f, 0x01, 0xf8, 0x48, 0x0f, 0x07 }, // swapgs; sysretq which is missing CLEAR_CPU_BUFFERS. It turns out dropping USERGS_SYSRET64 simplifies the code, allowing CLEAR_CPU_BUFFERS to be explicitly added to syscall_return_via_sysret path. Below is with CONFIG_PARAVIRT_XXL=y and this patch applied: syscall_return_via_sysret: ... <+342>: swapgs <+345>: xchg %ax,%ax <+347>: verw -0x1a2(%rip) <------ <+354>: sysretq ] En el kernel de Linux, se resolvió la siguiente vulnerabilidad: x86/xen: elimine el commit de llamada paravirt USERGS_SYSRET64 afd30525a659ac0ae0904f0cb4a2ca75522c3123 en sentido ascendente. USERGS_SYSRET64 se usa para regresar de una llamada al sistema a través de SYSRET, pero un invitado Xen PV usará la hiperllamada IRET, ya que no hay ninguna hiperllamada PV sysret definida. Entonces, en lugar de probar todos los requisitos previos para hacer un sysret y luego alterar la pila para Xen PV nuevamente para hacer un iret, simplemente use la salida iret desde el principio. • https://git.kernel.org/stable/c/cea750c99d8f6391080c420f811a46b21bad7cf4 https://git.kernel.org/stable/c/1424ab4bb386df9cc590c73afa55f13e9b00dea2 https://grsecurity.net/cve-2021-4440_linux_cna_case_study • CWE-400: Uncontrolled Resource Consumption •