In the Linux kernel, the following vulnerability has been resolved:
erofs: Fix detection of atomic context
Current check for atomic context is not sufficient as
z_erofs_decompressqueue_endio can be called under rcu lock
from blk_mq_flush_plug_list(). See the stacktrace [1]
In such case we should hand off the decompression work for async
processing rather than trying to do sync decompression in current
context. Patch fixes the detection by checking for
rcu_read_lock_any_held() and while at it use more appropriate
!in_task() check than in_atomic().
Background: Historically erofs would always schedule a kworker for
decompression which would incur the scheduling cost regardless of
the context. But z_erofs_decompressqueue_endio() may not always
be in atomic context and we could actually benefit from doing the
decompression in z_erofs_decompressqueue_endio() if we are in
thread context, for example when running with dm-verity.
This optimization was later added in patch [2] which has shown
improvement in performance benchmarks.
==============================================
[1] Problem stacktrace
[name:core&]BUG: sleeping function called from invalid context at kernel/locking/mutex.c:291
[name:core&]in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 1615, name: CpuMonitorServi
[name:core&]preempt_count: 0, expected: 0
[name:core&]RCU nest depth: 1, expected: 0
CPU: 7 PID: 1615 Comm: CpuMonitorServi Tainted: G S W OE 6.1.25-android14-5-maybe-dirty-mainline #1
Hardware name: MT6897 (DT)
Call trace:
dump_backtrace+0x108/0x15c
show_stack+0x20/0x30
dump_stack_lvl+0x6c/0x8c
dump_stack+0x20/0x48
__might_resched+0x1fc/0x308
__might_sleep+0x50/0x88
mutex_lock+0x2c/0x110
z_erofs_decompress_queue+0x11c/0xc10
z_erofs_decompress_kickoff+0x110/0x1a4
z_erofs_decompressqueue_endio+0x154/0x180
bio_endio+0x1b0/0x1d8
__dm_io_complete+0x22c/0x280
clone_endio+0xe4/0x280
bio_endio+0x1b0/0x1d8
blk_update_request+0x138/0x3a4
blk_mq_plug_issue_direct+0xd4/0x19c
blk_mq_flush_plug_list+0x2b0/0x354
__blk_flush_plug+0x110/0x160
blk_finish_plug+0x30/0x4c
read_pages+0x2fc/0x370
page_cache_ra_unbounded+0xa4/0x23c
page_cache_ra_order+0x290/0x320
do_sync_mmap_readahead+0x108/0x2c0
filemap_fault+0x19c/0x52c
__do_fault+0xc4/0x114
handle_mm_fault+0x5b4/0x1168
do_page_fault+0x338/0x4b4
do_translation_fault+0x40/0x60
do_mem_abort+0x60/0xc8
el0_da+0x4c/0xe0
el0t_64_sync_handler+0xd4/0xfc
el0t_64_sync+0x1a0/0x1a4
[2] Link: https://lore.kernel.org/all/20210317035448.13921-1-huangjianan@oppo.com/
In the Linux kernel, the following vulnerability has been resolved:
smb: client: fix warning in cifs_smb3_do_mount()
This fixes the following warning reported by kernel test robot
fs/smb/client/cifsfs.c:982 cifs_smb3_do_mount() warn: possible
memory leak of 'cifs_sb'
In the Linux kernel, the following vulnerability has been resolved:
rxrpc: Make it so that a waiting process can be aborted
When sendmsg() creates an rxrpc call, it queues it to wait for a connection
and channel to be assigned and then waits before it can start shovelling
data as the encrypted DATA packet content includes a summary of the
connection parameters.
However, sendmsg() may get interrupted before a connection gets assigned
and further sendmsg() calls will fail with EBUSY until an assignment is
made.
Fix this so that the call can at least be aborted without failing on
EBUSY. We have to be careful here as sendmsg() mustn't be allowed to start
the call timer if the call doesn't yet have a connection assigned as an
oops may follow shortly thereafter.
In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix memleak due to fentry attach failure
If it fails to attach fentry, the allocated bpf trampoline image will be
left in the system. That can be verified by checking /proc/kallsyms.
This meamleak can be verified by a simple bpf program as follows:
SEC("fentry/trap_init")
int fentry_run()
{
return 0;
}
It will fail to attach trap_init because this function is freed after
kernel init, and then we can find the trampoline image is left in the
system by checking /proc/kallsyms.
$ tail /proc/kallsyms
ffffffffc0613000 t bpf_trampoline_6442453466_1 [bpf]
ffffffffc06c3000 t bpf_trampoline_6442453466_1 [bpf]
$ bpftool btf dump file /sys/kernel/btf/vmlinux | grep "FUNC 'trap_init'"
[2522] FUNC 'trap_init' type_id=119 linkage=static
$ echo $((6442453466 & 0x7fffffff))
2522
Note that there are two left bpf trampoline images, that is because the
libbpf will fallback to raw tracepoint if -EINVAL is returned.
In the Linux kernel, the following vulnerability has been resolved:
wifi: mac80211_hwsim: Fix possible NULL dereference
In a call to mac80211_hwsim_select_tx_link() the sta pointer might
be NULL, thus need to check that it is not NULL before accessing it.
In the Linux kernel, the following vulnerability has been resolved:
netfilter: x_tables: fix percpu counter block leak on error path when creating new netns
Here is the stack where we allocate percpu counter block:
+-< __alloc_percpu
+-< xt_percpu_counter_alloc
+-< find_check_entry # {arp,ip,ip6}_tables.c
+-< translate_table
And it can be leaked on this code path:
+-> ip6t_register_table
+-> translate_table # allocates percpu counter block
+-> xt_register_table # fails
there is no freeing of the counter block on xt_register_table fail.
Note: xt_percpu_counter_free should be called to free it like we do in
do_replace through cleanup_entry helper (or in __ip6t_unregister_table).
Probability of hitting this error path is low AFAICS (xt_register_table
can only return ENOMEM here, as it is not replacing anything, as we are
creating new netns, and it is hard to imagine that all previous
allocations succeeded and after that one in xt_register_table failed).
But it's worth fixing even the rare leak.
In the Linux kernel, the following vulnerability has been resolved:
9p: set req refcount to zero to avoid uninitialized usage
When a new request is allocated, the refcount will be zero if it is
reused, but if the request is newly allocated from slab, it is not fully
initialized before being added to idr.
If the p9_read_work got a response before the refcount initiated. It will
use a uninitialized req, which will result in a bad request data struct.
Here is the logs from syzbot.
Corrupted memory at 0xffff88807eade00b [ 0xff 0x07 0x00 0x00 0x00 0x00
0x00 0x00 . . . . . . . . ] (in kfence-#110):
p9_fcall_fini net/9p/client.c:248 [inline]
p9_req_put net/9p/client.c:396 [inline]
p9_req_put+0x208/0x250 net/9p/client.c:390
p9_client_walk+0x247/0x540 net/9p/client.c:1165
clone_fid fs/9p/fid.h:21 [inline]
v9fs_fid_xattr_set+0xe4/0x2b0 fs/9p/xattr.c:118
v9fs_xattr_set fs/9p/xattr.c:100 [inline]
v9fs_xattr_handler_set+0x6f/0x120 fs/9p/xattr.c:159
__vfs_setxattr+0x119/0x180 fs/xattr.c:182
__vfs_setxattr_noperm+0x129/0x5f0 fs/xattr.c:216
__vfs_setxattr_locked+0x1d3/0x260 fs/xattr.c:277
vfs_setxattr+0x143/0x340 fs/xattr.c:309
setxattr+0x146/0x160 fs/xattr.c:617
path_setxattr+0x197/0x1c0 fs/xattr.c:636
__do_sys_setxattr fs/xattr.c:652 [inline]
__se_sys_setxattr fs/xattr.c:648 [inline]
__ia32_sys_setxattr+0xc0/0x160 fs/xattr.c:648
do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
__do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178
do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
entry_SYSENTER_compat_after_hwframe+0x70/0x82
Below is a similar scenario, the scenario in the syzbot log looks more
complicated than this one, but this patch can fix it.
T21124 p9_read_work
======================== second trans =================================
p9_client_walk
p9_client_rpc
p9_client_prepare_req
p9_tag_alloc
req = kmem_cache_alloc(p9_req_cache, GFP_NOFS);
tag = idr_alloc
<< preempted >>
req->tc.tag = tag;
/* req->[refcount/tag] == uninitialized */
m->rreq = p9_tag_lookup(m->client, m->rc.tag);
/* increments uninitalized refcount */
refcount_set(&req->refcount, 2);
/* cb drops one ref */
p9_client_cb(req)
/* reader thread drops its ref:
request is incorrectly freed */
p9_req_put(req)
/* use after free and ref underflow */
p9_req_put(req)
To fix it, we can initialize the refcount to zero before add to idr.
In the Linux kernel, the following vulnerability has been resolved:
ACPI: processor: idle: Check acpi_fetch_acpi_dev() return value
The return value of acpi_fetch_acpi_dev() could be NULL, which would
cause a NULL pointer dereference to occur in acpi_device_hid().
[ rjw: Subject and changelog edits, added empty line after if () ]
In the Linux kernel, the following vulnerability has been resolved:
erofs: fix order >= MAX_ORDER warning due to crafted negative i_size
As syzbot reported [1], the root cause is that i_size field is a
signed type, and negative i_size is also less than EROFS_BLKSIZ.
As a consequence, it's handled as fast symlink unexpectedly.
Let's fall back to the generic path to deal with such unusual i_size.
[1] https://lore.kernel.org/r/000000000000ac8efa05e7feaa1f@google.com