On Sun, Mar 29, 2015 at 5:13 AM, Borislav Petkov <bp@xxxxxxxxx> wrote: > On Sun, Mar 29, 2015 at 11:02:34AM +0200, Ingo Molnar wrote: >> So how about doing the patch below? >> >> Thanks, >> >> Ingo >> >> ===================================> >> From 6677d6f073cfda7f1036eb06d13faaad5c6742cc Mon Sep 17 00:00:00 2001 >> From: Ingo Molnar <mingo@xxxxxxxxxx> >> Date: Sun, 29 Mar 2015 09:10:08 +0200 >> Subject: [PATCH] x86/asm/entry: Remove user_mode_ignore_vm86() >> >> user_mode_ignore_vm86() can be used instead of user_mode(), in >> places where we have already done a v8086_mode() security >> check of ptregs. >> >> But doing this check in the wrong place would be a bug that could >> result in security problems, and also the naming still isn't very clear. >> >> Furthermore, it only affects 32-bit kernels, while most development >> happens on 64-bit kernels. >> >> If we replace them with user_mode() checks then the cost is only a >> very minor increase in various slowpaths: >> >> text data bss dec hex filename >> 10573391 703562 1753042 13029995 c6d26b vmlinux.o.before >> 10573423 703562 1753042 13030027 c6d28b vmlinux.o.after >> >> So lets get rid of this distinction once and for all. >> >> Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx> >> Cc: Borislav Petkov <bp@xxxxxxxxx> >> Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx> >> Cc: H. Peter Anvin <hpa@xxxxxxxxx> >> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> >> Cc: Oleg Nesterov <oleg@xxxxxxxxxx> >> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> >> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> >> --- >> arch/x86/include/asm/ptrace.h | 17 ----------------- >> arch/x86/kernel/cpu/perf_event.c | 2 +- >> arch/x86/kernel/traps.c | 6 +++--- >> 3 files changed, 4 insertions(+), 21 deletions(-) > > I had some doubts about people using user_mode_ignore_vm86() in the > wrong way and thus introducing sec. bugs. > > Since this is only on the slow path, simplifying the code makes sense to > me. > > Acked-by: Borislav Petkov <bp@xxxxxxx> > Ditto. Acked-by: Andy Lutomirski <luto@xxxxxxxxxx> > -- > Regards/Gruss, > Boris. > > ECO tip #101: Trim your mails when you reply. > -- -- Andy Lutomirski AMA Capital Management, LLC -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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