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| author | Andy Lutomirski <luto@kernel.org> | 2016-04-26 22:23:26 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-04-29 12:56:41 +0300 |
| commit | 45e876f794e8e566bf827c25ef0791875081724f (patch) | |
| tree | 0c725250ba4073785997ea5a74bdb1f7e84cb9d7 /arch/x86/mm/extable.c | |
| parent | f005f5d860e0231fe212cfda8c1a3148b99609f4 (diff) | |
| download | linux-45e876f794e8e566bf827c25ef0791875081724f.tar.xz | |
x86/segments/64: When loadsegment(fs, ...) fails, clear the base
On AMD CPUs, a failed loadsegment currently may not clear the FS
base. Fix it.
While we're at it, prevent loadsegment(gs, xyz) from even compiling
on 64-bit kernels. It shouldn't be used.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/a084c1b93b7b1408b58d3fd0b5d6e47da8e7d7cf.1461698311.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/mm/extable.c')
| -rw-r--r-- | arch/x86/mm/extable.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c index aaeda3ffaafe..4bb53b89f3c5 100644 --- a/arch/x86/mm/extable.c +++ b/arch/x86/mm/extable.c @@ -70,6 +70,16 @@ bool ex_handler_wrmsr_unsafe(const struct exception_table_entry *fixup, } EXPORT_SYMBOL(ex_handler_wrmsr_unsafe); +bool ex_handler_clear_fs(const struct exception_table_entry *fixup, + struct pt_regs *regs, int trapnr) +{ + if (static_cpu_has(X86_BUG_NULL_SEG)) + asm volatile ("mov %0, %%fs" : : "rm" (__USER_DS)); + asm volatile ("mov %0, %%fs" : : "rm" (0)); + return ex_handler_default(fixup, regs, trapnr); +} +EXPORT_SYMBOL(ex_handler_clear_fs); + bool ex_has_fault_handler(unsigned long ip) { const struct exception_table_entry *e; |