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Filename Latest commit message Latest commit date
Viacheslav Dubeyko fc56548fca hfs: fix KMSAN uninit-value issue in hfs_find_set_zero_bits()
[ Upstream commit 2048ec5b98dbdfe0b929d2e42dc7a54c389c53dd ]

The syzbot reported issue in hfs_find_set_zero_bits():

=====================================================
BUG: KMSAN: uninit-value in hfs_find_set_zero_bits+0x74d/0xb60 fs/hfs/bitmap.c:45
 hfs_find_set_zero_bits+0x74d/0xb60 fs/hfs/bitmap.c:45
 hfs_vbm_search_free+0x13c/0x5b0 fs/hfs/bitmap.c:151
 hfs_extend_file+0x6a5/0x1b00 fs/hfs/extent.c:408
 hfs_get_block+0x435/0x1150 fs/hfs/extent.c:353
 __block_write_begin_int+0xa76/0x3030 fs/buffer.c:2151
 block_write_begin fs/buffer.c:2262 [inline]
 cont_write_begin+0x10e1/0x1bc0 fs/buffer.c:2601
 hfs_write_begin+0x85/0x130 fs/hfs/inode.c:52
 cont_expand_zero fs/buffer.c:2528 [inline]
 cont_write_begin+0x35a/0x1bc0 fs/buffer.c:2591
 hfs_write_begin+0x85/0x130 fs/hfs/inode.c:52
 hfs_file_truncate+0x1d6/0xe60 fs/hfs/extent.c:494
 hfs_inode_setattr+0x964/0xaa0 fs/hfs/inode.c:654
 notify_change+0x1993/0x1aa0 fs/attr.c:552
 do_truncate+0x28f/0x310 fs/open.c:68
 do_ftruncate+0x698/0x730 fs/open.c:195
 do_sys_ftruncate fs/open.c:210 [inline]
 __do_sys_ftruncate fs/open.c:215 [inline]
 __se_sys_ftruncate fs/open.c:213 [inline]
 __x64_sys_ftruncate+0x11b/0x250 fs/open.c:213
 x64_sys_call+0xfe3/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:78
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:4154 [inline]
 slab_alloc_node mm/slub.c:4197 [inline]
 __kmalloc_cache_noprof+0x7f7/0xed0 mm/slub.c:4354
 kmalloc_noprof include/linux/slab.h:905 [inline]
 hfs_mdb_get+0x1cc8/0x2a90 fs/hfs/mdb.c:175
 hfs_fill_super+0x3d0/0xb80 fs/hfs/super.c:337
 get_tree_bdev_flags+0x6e3/0x920 fs/super.c:1681
 get_tree_bdev+0x38/0x50 fs/super.c:1704
 hfs_get_tree+0x35/0x40 fs/hfs/super.c:388
 vfs_get_tree+0xb0/0x5c0 fs/super.c:1804
 do_new_mount+0x738/0x1610 fs/namespace.c:3902
 path_mount+0x6db/0x1e90 fs/namespace.c:4226
 do_mount fs/namespace.c:4239 [inline]
 __do_sys_mount fs/namespace.c:4450 [inline]
 __se_sys_mount+0x6eb/0x7d0 fs/namespace.c:4427
 __x64_sys_mount+0xe4/0x150 fs/namespace.c:4427
 x64_sys_call+0xfa7/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 1 UID: 0 PID: 12609 Comm: syz.1.2692 Not tainted 6.16.0-syzkaller #0 PREEMPT(none)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
=====================================================

The HFS_SB(sb)->bitmap buffer is allocated in hfs_mdb_get():

HFS_SB(sb)->bitmap = kmalloc(8192, GFP_KERNEL);

Finally, it can trigger the reported issue because kmalloc()
doesn't clear the allocated memory. If allocated memory contains
only zeros, then everything will work pretty fine.
But if the allocated memory contains the "garbage", then
it can affect the bitmap operations and it triggers
the reported issue.

This patch simply exchanges the kmalloc() on kzalloc()
with the goal to guarantee the correctness of bitmap operations.
Because, newly created allocation bitmap should have all
available blocks free. Potentially, initialization bitmap's read
operation could not fill the whole allocated memory and
"garbage" in the not initialized memory will be the reason of
volume coruptions and file system driver bugs.

Reported-by: syzbot <syzbot+773fa9d79b29bd8b6831@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=773fa9d79b29bd8b6831
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
cc: Yangtao Li <frank.li@vivo.com>
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20250820230636.179085-1-slava@dubeyko.com
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-10-29 13:59:58 +01:00
arch KVM: x86: Don't (re)check L1 intercepts when completing userspace I/O 2025-10-29 13:59:54 +01:00
block block: use int to store blk_stack_limits() return value 2025-10-29 13:59:46 +01:00
certs
crypto crypto: essiv - Check ssize for decryption and in-place encryption 2025-10-29 13:59:52 +01:00
Documentation fs: Add 'initramfs_options' to set initramfs mount options 2025-10-29 13:59:55 +01:00
drivers tg3: prevent use of uninitialized remote_adv and local_adv variables 2025-10-29 13:59:57 +01:00
fs hfs: fix KMSAN uninit-value issue in hfs_find_set_zero_bits() 2025-10-29 13:59:58 +01:00
include net/ip6_tunnel: Prevent perpetual tunnel growth 2025-10-29 13:59:56 +01:00
init bpfilter: match bit size of bpfilter_umh to that of the kernel 2025-07-17 18:24:51 +02:00
ipc
kernel sched/fair: Fix pelt lost idle time detection 2025-10-29 13:59:57 +01:00
lib lib/genalloc: fix device leak in of_gen_pool_get() 2025-10-29 13:59:53 +01:00
LICENSES
mm mm: hugetlb: avoid soft lockup when mprotect to large memory area 2025-10-29 13:59:50 +01:00
net tls: don't rely on tx_work during send() 2025-10-29 13:59:57 +01:00
samples samples: mei: Fix building on musl libc 2025-08-28 16:21:19 +02:00
scripts randstruct: gcc-plugin: Fix attribute addition 2025-09-09 18:44:01 +02:00
security securityfs: don't pin dentries twice, once is enough... 2025-08-28 16:21:24 +02:00
sound ALSA: firewire: amdtp-stream: fix enum kernel-doc warnings 2025-10-29 13:59:57 +01:00
tools rseq/selftests: Use weak symbol reference, not definition, to link with glibc 2025-10-29 13:59:54 +01:00
usr kbuild: hdrcheck: fix cross build with clang 2025-07-17 18:24:51 +02:00
virt
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS platform: Add Surface platform directory 2025-06-27 11:02:56 +01:00
Makefile Linux 5.4.300 2025-10-02 13:34:35 +02:00
README

Linux kernel
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Please read the Documentation/process/changes.rst file, as it contains the
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