The following warning was triggered on a hardware environment:
SELinux: Converting 162 SID table entries...
BUG: sleeping function called from invalid context at
__might_sleep+0x60/0x74 0x0
in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 5943, name: tar
CPU: 7 PID: 5943 Comm: tar Tainted: P O 5.10.0 #1
Call trace:
dump_backtrace+0x0/0x1c8
show_stack+0x18/0x28
dump_stack+0xe8/0x15c
___might_sleep+0x168/0x17c
__might_sleep+0x60/0x74
__kmalloc_track_caller+0xa0/0x7dc
kstrdup+0x54/0xac
convert_context+0x48/0x2e4
sidtab_context_to_sid+0x1c4/0x36c
security_context_to_sid_core+0x168/0x238
security_context_to_sid_default+0x14/0x24
inode_doinit_use_xattr+0x164/0x1e4
inode_doinit_with_dentry+0x1c0/0x488
selinux_d_instantiate+0x20/0x34
security_d_instantiate+0x70/0xbc
d_splice_alias+0x4c/0x3c0
ext4_lookup+0x1d8/0x200 [ext4]
__lookup_slow+0x12c/0x1e4
walk_component+0x100/0x200
path_lookupat+0x88/0x118
filename_lookup+0x98/0x130
user_path_at_empty+0x48/0x60
vfs_statx+0x84/0x140
vfs_fstatat+0x20/0x30
__se_sys_newfstatat+0x30/0x74
__arm64_sys_newfstatat+0x1c/0x2c
el0_svc_common.constprop.0+0x100/0x184
do_el0_svc+0x1c/0x2c
el0_svc+0x20/0x34
el0_sync_handler+0x80/0x17c
el0_sync+0x13c/0x140
SELinux: Context system_u:object_r:pssp_rsyslog_log_t:s0:c0 is
not valid (left unmapped).
It was found that within a critical section of spin_lock_irqsave in
sidtab_context_to_sid(), convert_context() (hooked by
sidtab_convert_params.func) might cause the process to sleep via
allocating memory with GFP_KERNEL, which is problematic.
As Ondrej pointed out [1], convert_context()/sidtab_convert_params.func
has another caller sidtab_convert_tree(), which is okay with GFP_KERNEL.
Therefore, fix this problem by adding a gfp_t argument for
convert_context()/sidtab_convert_params.func and pass GFP_KERNEL/_ATOMIC
properly in individual callers.
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20221018120111.1474581-1-gongruiqi1@huawei.com/ [1]
Reported-by: Tan Ninghao <tanninghao1@huawei.com>
Fixes: ee1a84fdfe ("selinux: overhaul sidtab to fix bug and improve performance")
Signed-off-by: GONG, Ruiqi <gongruiqi1@huawei.com>
Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com>
[PM: wrap long BUG() output lines, tweak subject line]
Signed-off-by: Paul Moore <paul@paul-moore.com>
abe3c63144