The following commit has been merged into the x86/mm branch of tip: Commit-ID: 5042d40a264c8a508d58ed71e4c07b05175b3635 Gitweb: https://git.kernel.org/tip/5042d40a264c8a508d58ed71e4c07b05175b3635 Author: Andy Lutomirski <l...@kernel.org> AuthorDate: Tue, 09 Feb 2021 18:33:42 -08:00 Committer: Borislav Petkov <b...@suse.de> CommitterDate: Wed, 10 Feb 2021 14:39:52 +01:00
x86/fault: Bypass no_context() for implicit kernel faults from usermode Drop an indentation level and remove the last user_mode(regs) == true caller of no_context() by directly OOPSing for implicit kernel faults from usermode. Signed-off-by: Andy Lutomirski <l...@kernel.org> Signed-off-by: Borislav Petkov <b...@suse.de> Link: https://lkml.kernel.org/r/6e3d1129494a8de1e59d28012286e3a292a2296e.1612924255.git.l...@kernel.org --- arch/x86/mm/fault.c | 59 +++++++++++++++++++++++--------------------- 1 file changed, 32 insertions(+), 27 deletions(-) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index dbf6a94..187975b 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -826,44 +826,49 @@ __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code, { struct task_struct *tsk = current; - /* User mode accesses just cause a SIGSEGV */ - if (user_mode(regs) && (error_code & X86_PF_USER)) { - /* - * It's possible to have interrupts off here: - */ - local_irq_enable(); + if (!user_mode(regs)) { + no_context(regs, error_code, address, pkey, si_code); + return; + } - /* - * Valid to do another page fault here because this one came - * from user space: - */ - if (is_prefetch(regs, error_code, address)) - return; + if (!(error_code & X86_PF_USER)) { + /* Implicit user access to kernel memory -- just oops */ + page_fault_oops(regs, error_code, address); + return; + } - if (is_errata100(regs, address)) - return; + /* + * User mode accesses just cause a SIGSEGV. + * It's possible to have interrupts off here: + */ + local_irq_enable(); - sanitize_error_code(address, &error_code); + /* + * Valid to do another page fault here because this one came + * from user space: + */ + if (is_prefetch(regs, error_code, address)) + return; - if (fixup_vdso_exception(regs, X86_TRAP_PF, error_code, address)) - return; + if (is_errata100(regs, address)) + return; - if (likely(show_unhandled_signals)) - show_signal_msg(regs, error_code, address, tsk); + sanitize_error_code(address, &error_code); - set_signal_archinfo(address, error_code); + if (fixup_vdso_exception(regs, X86_TRAP_PF, error_code, address)) + return; - if (si_code == SEGV_PKUERR) - force_sig_pkuerr((void __user *)address, pkey); + if (likely(show_unhandled_signals)) + show_signal_msg(regs, error_code, address, tsk); - force_sig_fault(SIGSEGV, si_code, (void __user *)address); + set_signal_archinfo(address, error_code); - local_irq_disable(); + if (si_code == SEGV_PKUERR) + force_sig_pkuerr((void __user *)address, pkey); - return; - } + force_sig_fault(SIGSEGV, si_code, (void __user *)address); - no_context(regs, error_code, address, SIGSEGV, si_code); + local_irq_disable(); } static noinline void
