On Wed, Oct 19, 2022 at 4:56 AM GONG, Ruiqi <gongruiqi1@xxxxxxxxxx> wrote: > > 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. > > Link: https://lore.kernel.org/all/20221018120111.1474581-1-gongruiqi1@xxxxxxxxxx/ [1] > Reported-by: Tan Ninghao <tanninghao1@xxxxxxxxxx> > Fixes: ee1a84fdfeed ("selinux: overhaul sidtab to fix bug and improve performance") > Signed-off-by: GONG, Ruiqi <gongruiqi1@xxxxxxxxxx> > --- > > v2: change as Ondrej suggests & redraft commit message This looks good, thanks! Reviewed-by: Ondrej Mosnacek <omosnace@xxxxxxxxxx> > [...] -- Ondrej Mosnacek Senior Software Engineer, Linux Security - SELinux kernel Red Hat, Inc.
