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| author | Peter Zijlstra <peterz@infradead.org> | 2021-09-17 11:20:04 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-09-21 13:52:18 +0200 |
| commit | b968e84b509da593c50dc3db679e1d33de701f78 (patch) | |
| tree | 0964cb6b0de25acd19649ade20648761e7dbed67 /arch/x86/kernel/process.c | |
| parent | 6880fa6c56601bb8ed59df6c30fd390cc5f6dd8f (diff) | |
| download | linux-b968e84b509da593c50dc3db679e1d33de701f78.tar.gz linux-b968e84b509da593c50dc3db679e1d33de701f78.tar.bz2 linux-b968e84b509da593c50dc3db679e1d33de701f78.zip | |
x86/iopl: Fake iopl(3) CLI/STI usage
Since commit c8137ace5638 ("x86/iopl: Restrict iopl() permission
scope") it's possible to emulate iopl(3) using ioperm(), except for
the CLI/STI usage.
Userspace CLI/STI usage is very dubious (read broken), since any
exception taken during that window can lead to rescheduling anyway (or
worse). The IOPL(2) manpage even states that usage of CLI/STI is highly
discouraged and might even crash the system.
Of course, that won't stop people and HP has the dubious honour of
being the first vendor to be found using this in their hp-health
package.
In order to enable this 'software' to still 'work', have the #GP treat
the CLI/STI instructions as NOPs when iopl(3). Warn the user that
their program is doing dubious things.
Fixes: a24ca9976843 ("x86/iopl: Remove legacy IOPL option")
Reported-by: Ondrej Zary <linux@zary.sk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@kernel.org # v5.5+
Link: https://lkml.kernel.org/r/20210918090641.GD5106@worktop.programming.kicks-ass.net
Diffstat (limited to 'arch/x86/kernel/process.c')
| -rw-r--r-- | arch/x86/kernel/process.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 1d9463e3096b..f2f733bcb2b9 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -132,6 +132,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg, frame->ret_addr = (unsigned long) ret_from_fork; p->thread.sp = (unsigned long) fork_frame; p->thread.io_bitmap = NULL; + p->thread.iopl_warn = 0; memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps)); #ifdef CONFIG_X86_64 |