kernel/git/stable/linux.git/arch/x86/entry, branch linux-5.8.y

x86/irq: Make run_on_irqstack_cond() typesafe

2020-10-01T15:36:32+00:00

commit a7b3474cbb2864d5500d5e4f48dd57c903975cab upstream. Sami reported that run_on_irqstack_cond() requires the caller to cast functions to mismatching types, which trips indirect call Control-Flow Integrity (CFI) in Clang. Instead of disabling CFI on that function, provide proper helpers for the three call variants. The actual ASM code stays the same as that is out of reach. [ bp: Fix __run_on_irqstack() prototype to match. ] Fixes: 931b94145981 ("x86/entry: Provide helpers for executing on the irqstack") Reported-by: Nathan Chancellor Reported-by: Sami Tolvanen Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Tested-by: Sami Tolvanen Cc: Link: https://github.com/ClangBuiltLinux/linux/issues/1052 Link: https://lkml.kernel.org/r/87pn6eb5tv.fsf@nanos.tec.linutronix.de Signed-off-by: Greg Kroah-Hartman

x86/entry: Fix AC assertion

2020-09-09T17:14:24+00:00

commit 662a0221893a3d58aa72719671844264306f6e4b upstream. The WARN added in commit 3c73b81a9164 ("x86/entry, selftests: Further improve user entry sanity checks") unconditionally triggers on a IVB machine because it does not support SMAP. For !SMAP hardware the CLAC/STAC instructions are patched out and thus if userspace sets AC, it is still have set after entry. Fixes: 3c73b81a9164 ("x86/entry, selftests: Further improve user entry sanity checks") Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Thomas Gleixner Tested-by: Daniel Thompson Acked-by: Andy Lutomirski Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20200902133200.666781610@infradead.org Signed-off-by: Greg Kroah-Hartman

x86/entry: Actually disable stack protector

2020-07-19T11:07:10+00:00

Some builds of GCC enable stack protector by default. Simply removing the arguments is not sufficient to disable stack protector, as the stack protector for those GCC builds must be explicitly disabled. Remove the argument removals and add -fno-stack-protector. Additionally include missed x32 argument updates, and adjust whitespace for readability. Fixes: 20355e5f73a7 ("x86/entry: Exclude low level entry code from sanitizing") Signed-off-by: Kees Cook Signed-off-by: Thomas Gleixner Link: https://lkml.kernel.org/r/202006261333.585319CA6B@keescook

x86/entry/common: Make prepare_exit_to_usermode() static

2020-07-09T09:18:30+00:00

No users outside this file anymore. Signed-off-by: Thomas Gleixner Acked-by: Andy Lutomirski Link: https://lkml.kernel.org/r/20200708192934.301116609@linutronix.de

x86/entry: Mark check_user_regs() noinstr

2020-07-09T09:18:29+00:00

It's called from the non-instrumentable section. Fixes: c9c26150e61d ("x86/entry: Assert that syscalls are on the right stack") Signed-off-by: Thomas Gleixner Acked-by: Andy Lutomirski Link: https://lkml.kernel.org/r/20200708192934.191497962@linutronix.de

x86/entry, selftests: Further improve user entry sanity checks

2020-07-04T17:47:25+00:00

Chasing down a Xen bug caused me to realize that the new entry sanity checks are still fairly weak. Add some more checks. Signed-off-by: Andy Lutomirski Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/881de09e786ab93ce56ee4a2437ba2c308afe7a9.1593795633.git.luto@kernel.org

x86/entry/compat: Clear RAX high bits on Xen PV SYSENTER

2020-07-04T17:47:25+00:00

Move the clearing of the high bits of RAX after Xen PV joins the SYSENTER path so that Xen PV doesn't skip it. Arguably this code should be deleted instead, but that would belong in the merge window. Fixes: ffae641f5747 ("x86/entry/64/compat: Fix Xen PV SYSENTER frame setup") Signed-off-by: Andy Lutomirski Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/9d33b3f3216dcab008070f1c28b6091ae7199969.1593795633.git.luto@kernel.org

x86/entry/64/compat: Fix Xen PV SYSENTER frame setup

2020-07-01T08:00:26+00:00

The SYSENTER frame setup was nonsense. It worked by accident because the normal code into which the Xen asm jumped (entry_SYSENTER_32/compat) threw away SP without touching the stack. entry_SYSENTER_compat was recently modified such that it relied on having a valid stack pointer, so now the Xen asm needs to invoke it with a valid stack. Fix it up like SYSCALL: use the Xen-provided frame and skip the bare metal prologue. Fixes: 1c3e5d3f60e2 ("x86/entry: Make entry_64_compat.S objtool clean") Signed-off-by: Andy Lutomirski Signed-off-by: Thomas Gleixner Reviewed-by: Boris Ostrovsky Link: https://lkml.kernel.org/r/947880c41ade688ff4836f665d0c9fcaa9bd1201.1593191971.git.luto@kernel.org

x86/entry: Move SYSENTER's regs->sp and regs->flags fixups into C

2020-07-01T08:00:25+00:00

The SYSENTER asm (32-bit and compat) contains fixups for regs->sp and regs->flags. Move the fixups into C and fix some comments while at it. This is a valid cleanup all by itself, and it also simplifies the subsequent patch that will fix Xen PV SYSENTER. Signed-off-by: Andy Lutomirski Signed-off-by: Thomas Gleixner Link: https://lkml.kernel.org/r/fe62bef67eda7fac75b8f3dbafccf571dc4ece6b.1593191971.git.luto@kernel.org

x86/entry: Assert that syscalls are on the right stack

2020-07-01T08:00:25+00:00

Now that the entry stack is a full page, it's too easy to regress the system call entry code and end up on the wrong stack without noticing. Assert that all system calls (SYSCALL64, SYSCALL32, SYSENTER, and INT80) are on the right stack and have pt_regs in the right place. Signed-off-by: Andy Lutomirski Signed-off-by: Thomas Gleixner Link: https://lkml.kernel.org/r/52059e42bb0ab8551153d012d68f7be18d72ff8e.1593191971.git.luto@kernel.org