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x86/fault: Fix wrong signal when vsyscall fails with pkey
The function __bad_area_nosemaphore() calls kernelmode_fixup_or_oops()
with the parameter @signal being actually @pkey, which will send a
signal numbered with the argument in @pkey.
This bug can be triggered when the kernel fails to access user-given
memory pages that are protected by a pkey, so it can go down the
do_user_addr_fault() path and pass the !user_mode() check in
__bad_area_nosemaphore().
Most cases will simply run the kernel fixup code to make an -EFAULT. But
when another condition current->thread.sig_on_uaccess_err is met, which
is only used to emulate vsyscall, the kernel will generate the wrong
signal.
Add a new parameter @pkey to kernelmode_fixup_or_oops() to fix this.
[ bp: Massage commit message, fix build error as reported by the 0day
bot: https://lkml.kernel.org/r/202109202245.APvuT8BX-lkp@intel.com ]
Fixes: 5042d40a26
("x86/fault: Bypass no_context() for implicit kernel faults from usermode")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Jiashuo Liang <liangjs@pku.edu.cn>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/20210730030152.249106-1-liangjs@pku.edu.cn
This commit is contained in:
parent
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commit
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@ -2,8 +2,6 @@
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#ifndef _ASM_X86_PKEYS_H
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#define _ASM_X86_PKEYS_H
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#define ARCH_DEFAULT_PKEY 0
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/*
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* If more than 16 keys are ever supported, a thorough audit
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* will be necessary to ensure that the types that store key
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@ -710,7 +710,8 @@ oops:
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static noinline void
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kernelmode_fixup_or_oops(struct pt_regs *regs, unsigned long error_code,
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unsigned long address, int signal, int si_code)
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unsigned long address, int signal, int si_code,
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u32 pkey)
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{
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WARN_ON_ONCE(user_mode(regs));
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@ -735,8 +736,12 @@ kernelmode_fixup_or_oops(struct pt_regs *regs, unsigned long error_code,
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set_signal_archinfo(address, error_code);
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/* XXX: hwpoison faults will set the wrong code. */
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force_sig_fault(signal, si_code, (void __user *)address);
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if (si_code == SEGV_PKUERR) {
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force_sig_pkuerr((void __user *)address, pkey);
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} else {
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/* XXX: hwpoison faults will set the wrong code. */
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force_sig_fault(signal, si_code, (void __user *)address);
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}
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}
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/*
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@ -798,7 +803,8 @@ __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
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struct task_struct *tsk = current;
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if (!user_mode(regs)) {
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kernelmode_fixup_or_oops(regs, error_code, address, pkey, si_code);
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kernelmode_fixup_or_oops(regs, error_code, address,
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SIGSEGV, si_code, pkey);
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return;
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}
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@ -930,7 +936,8 @@ do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address,
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{
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/* Kernel mode? Handle exceptions or die: */
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if (!user_mode(regs)) {
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kernelmode_fixup_or_oops(regs, error_code, address, SIGBUS, BUS_ADRERR);
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kernelmode_fixup_or_oops(regs, error_code, address,
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SIGBUS, BUS_ADRERR, ARCH_DEFAULT_PKEY);
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return;
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}
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@ -1396,7 +1403,8 @@ good_area:
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*/
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if (!user_mode(regs))
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kernelmode_fixup_or_oops(regs, error_code, address,
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SIGBUS, BUS_ADRERR);
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SIGBUS, BUS_ADRERR,
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ARCH_DEFAULT_PKEY);
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return;
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}
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@ -1416,7 +1424,8 @@ good_area:
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return;
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if (fatal_signal_pending(current) && !user_mode(regs)) {
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kernelmode_fixup_or_oops(regs, error_code, address, 0, 0);
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kernelmode_fixup_or_oops(regs, error_code, address,
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0, 0, ARCH_DEFAULT_PKEY);
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return;
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}
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@ -1424,7 +1433,8 @@ good_area:
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/* Kernel mode? Handle exceptions or die: */
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if (!user_mode(regs)) {
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kernelmode_fixup_or_oops(regs, error_code, address,
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SIGSEGV, SEGV_MAPERR);
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SIGSEGV, SEGV_MAPERR,
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ARCH_DEFAULT_PKEY);
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return;
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}
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@ -4,6 +4,8 @@
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#include <linux/mm.h>
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#define ARCH_DEFAULT_PKEY 0
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#ifdef CONFIG_ARCH_HAS_PKEYS
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#include <asm/pkeys.h>
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#else /* ! CONFIG_ARCH_HAS_PKEYS */
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