[amd64] asm/traps: Disable tracing and kprobes in fixup_bad_iret and sync_regs

svn path=/dists/sid/linux/; revision=22140

debian/changelog

@@ -245,6 +245,8 @@ linux (3.16.7-ckt2-1) UNRELEASED; urgency=medium
   * [amd64] traps: Stop using IST for #SS (CVE-2014-9090)
   * [amd64] traps: Fix the espfix64 #DF fixup and rewrite it in C
   * [amd64] traps: Rework bad_iret
+  * [amd64] asm/traps: Disable tracing and kprobes in fixup_bad_iret and
+    sync_regs
   * Fix ABI changes in iovec, of, perf and truncate
   * Ignore ABI changes in iwlwifi, KVM and spi-nor
   * Revert "drivers/net: Disable UFO through virtio" in macvtap and tun.

debian/patches/bugfix/x86/x86-asm-traps-Disable-tracing-and-kprobes-in-fixup_b.patch

@@ -0,0 +1,50 @@
+From: Andy Lutomirski <luto@amacapital.net>
+Date: Mon, 24 Nov 2014 17:39:06 -0800
+Subject: x86/asm/traps: Disable tracing and kprobes in fixup_bad_iret and
+ sync_regs
+Origin: https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git/commit?id=7ddc6a2199f1da405a2fb68c40db8899b1a8cd87
+
+These functions can be executed on the int3 stack, so kprobes
+are dangerous. Tracing is probably a bad idea, too.
+
+Fixes: b645af2d5905 ("x86_64, traps: Rework bad_iret")
+Signed-off-by: Andy Lutomirski <luto@amacapital.net>
+Cc: <stable@vger.kernel.org> # Backport as far back as it would apply
+Cc: Linus Torvalds <torvalds@linux-foundation.org>
+Cc: Steven Rostedt <rostedt@goodmis.org>
+Link: http://lkml.kernel.org/r/50e33d26adca60816f3ba968875801652507d0c4.1416870125.git.luto@amacapital.net
+Signed-off-by: Ingo Molnar <mingo@kernel.org>
+---
+ arch/x86/kernel/traps.c | 5 +++--
+ 1 file changed, 3 insertions(+), 2 deletions(-)
+
+diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
+index de801f2..07ab8e9 100644
+--- a/arch/x86/kernel/traps.c
++++ b/arch/x86/kernel/traps.c
+@@ -387,7 +387,7 @@ NOKPROBE_SYMBOL(do_int3);
+  * for scheduling or signal handling. The actual stack switch is done in
+  * entry.S
+  */
+-asmlinkage __visible struct pt_regs *sync_regs(struct pt_regs *eregs)
++asmlinkage __visible notrace struct pt_regs *sync_regs(struct pt_regs *eregs)
+ {
+ 	struct pt_regs *regs = eregs;
+ 	/* Did already sync */
+@@ -413,7 +413,7 @@ struct bad_iret_stack {
+ 	struct pt_regs regs;
+ };
+ 
+-asmlinkage __visible
++asmlinkage __visible notrace
+ struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s)
+ {
+ 	/*
+@@ -436,6 +436,7 @@ struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s)
+ 	BUG_ON(!user_mode_vm(&new_stack->regs));
+ 	return new_stack;
+ }
++NOKPROBE_SYMBOL(fixup_bad_iret);
+ #endif
+ 
+ /*

debian/patches/series

@@ -62,6 +62,7 @@ bugfix/arm64/arm64-removed-using-of-the-mask-attribute-in-the-dts.patch
 bugfix/x86/x86_64-traps-Stop-using-IST-for-SS.patch
 bugfix/x86/x86_64-traps-Fix-the-espfix64-DF-fixup-and-rewrite-i.patch
 bugfix/x86/x86_64-traps-Rework-bad_iret.patch
+bugfix/x86/x86-asm-traps-Disable-tracing-and-kprobes-in-fixup_b.patch
 
 # Arch features
 features/mips/MIPS-Support-hard-limit-of-cpu-count-nr_cpu_ids.patch