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x86/ioperm: Prevent NULL dereference on theoretical missing IO bitmap

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Outside the IOPL emulation path, the IO bitmap is always expected
to be allocated when TIF_IO_BITMAP is set. The paranoid WARN_ON_ONCE()
handles the case where the flag and the pointer got out of sync.
In this theoretical scenario, which presumes some other bug in the
code that triggers the WARN_ON_ONCe(), return early, instead of
continuing and dereferencing a NULL pointer.

[ mingo: Clarified the changelog. ]

Signed-off-by: Li RongQing <lirongqing@baidu.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Sohil Mehta <sohil.mehta@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Link: https://patch.msgid.link/20260615070115.4720-1-lirongqing@baidu.com
This commit is contained in:
Li RongQing 2026-06-15 15:01:15 +08:00 committed by Ingo Molnar
parent 8cd9520d35
commit 2d36d3b451
1 changed files with 1 additions and 0 deletions
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arch/x86/kernel/process.c
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@ -486,6 +486,7 @@ void native_tss_update_io_bitmap(void)
if (WARN_ON_ONCE(!iobm)) {
clear_thread_flag(TIF_IO_BITMAP);
native_tss_invalidate_io_bitmap();
return;
}
/*