From: Borislav Petkov <bp@alien8.de>
To: Dave Hansen <dave@sr71.net>
Cc: hpa@linux.intel.com, linux-kernel@vger.kernel.org, x86@kernel.org
Subject: Re: [PATCH 1/5] clean up checks against "high_memory" variable
Date: Thu, 11 Apr 2013 02:44:50 +0200 [thread overview]
Message-ID: <20130411004449.GB17544@pd.tnic> (raw)
In-Reply-To: <20130410233250.FF8E7E2D@viggo.jf.intel.com>
On Wed, Apr 10, 2013 at 04:32:50PM -0700, Dave Hansen wrote:
>
> We have a new debugging check on x86 that has caught a number
> of long-standing bugs. However, there is a _bit_ of collateral
> damage with things that call __pa(high_memory).
>
> We are now checking that any addresses passed to __pa() are
> *valid* and can be dereferenced.
>
> "high_memory", however, is not valid. It marks the start of
> highmem, and isn't itself a valid pointer. But, those users
> are really just asking "is this vaddr mapped"? So, give them
> a helper that does that, plus is also kind to our new
> debugging check.
>
> Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
FWIW,
this one already fixes the BUG below I'm seeing when booting 32-bit
Atom guests in qemu.
Tested-by: Borislav Petkov <bp@suse.de>
More testing tomorrow.
[ 57.035880] ------------[ cut here ]------------
[ 57.036190] kernel BUG at arch/x86/mm/physaddr.c:79!
[ 57.036190] invalid opcode: 0000 [#1] PREEMPT SMP
[ 57.036190] Modules linked in:
[ 57.036190] Pid: 2555, comm: wdm Tainted: G S W 3.9.0-rc6+ #5 Bochs Bochs
[ 57.036190] EIP: 0060:[<c10321b1>] EFLAGS: 00010206 CPU: 56
[ 57.036190] EIP is at __phys_addr+0x71/0x80
[ 57.036190] EAX: 00000000 EBX: 373fe000 ECX: 0000000c EDX: 00000000
[ 57.036190] ESI: 00000000 EDI: 00002000 EBP: ec509f40 ESP: ec509f3c
[ 57.036190] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
[ 57.036190] CR0: 8005003b CR2: b7620b48 CR3: 2f5b5000 CR4: 000006d0
[ 57.036190] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
[ 57.036190] DR6: ffff0ff0 DR7: 00000400
[ 57.036190] Process wdm (pid: 2555, ti=ec508000 task=ec500000 task.ti=ec508000)
[ 57.036190] Stack:
[ 57.036190] 00002000 ec509f64 c1304268 ec570000 ec50e300 bf87299c 00002000 ec50e300
[ 57.036190] c1304240 00002000 ec509f8c c1120276 ec509f98 00000000 ed540314 c1304240
[ 57.036190] ec570000 ec50e300 00000000 08065294 ec509fac c1120488 ec509f98 00000000
[ 57.036190] Call Trace:
[ 57.036190] [<c1304268>] read_mem+0x28/0xf0
[ 57.036190] [<c1304240>] ? write_mem+0xf0/0xf0
[ 57.036190] [<c1120276>] vfs_read+0x86/0x140
[ 57.036190] [<c1304240>] ? write_mem+0xf0/0xf0
[ 57.036190] [<c1120488>] sys_read+0x48/0x90
[ 57.036190] [<c15231fe>] sysenter_do_call+0x12/0x36
[ 57.036190] Code: 39 0b c2 81 c2 00 00 80 00 39 d0 72 cc 8b 15 2c 4c 74 c1 81 ea 00 a0 a4 00 81 e2 00 00 c0 ff 81 ea 00 20 00 00 39 d0 73 b0 0f 0b <0f> 0b 0f 0b 8d 74 26 00 8d bc 27 00 00 00 00 55 89 e5 53 3e 8d
[ 57.036190] EIP: [<c10321b1>] __phys_addr+0x71/0x80 SS:ESP 0068:ec509f3c
[ 57.619214] ---[ end trace 4e05f3724c460358 ]---
--
Regards/Gruss,
Boris.
Sent from a fat crate under my desk. Formatting is fine.
--
next prev parent reply other threads:[~2013-04-11 0:44 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-10 23:32 [PATCH 0/5] [RFC] rework /dev/mem code vs. highmem and DEBUG_VIRTUAL Dave Hansen
2013-04-10 23:32 ` [PATCH 1/5] clean up checks against "high_memory" variable Dave Hansen
2013-04-11 0:44 ` Borislav Petkov [this message]
2013-04-10 23:32 ` [PATCH 2/5] make /dev/kmem return error for highmem Dave Hansen
2013-04-11 9:58 ` Borislav Petkov
2013-04-10 23:32 ` [PATCH 3/5] avoid /dev/kmem oopses with DEBUG_VIRTUAL Dave Hansen
2013-04-10 23:32 ` [PATCH 4/5] break up slow_virt_to_phys() Dave Hansen
2013-04-11 12:29 ` Borislav Petkov
2013-04-11 16:28 ` Dave Hansen
2013-04-11 17:12 ` Borislav Petkov
2013-04-10 23:32 ` [PATCH 5/5] keep /dev/kmem from triggering BUG_ON() with DEBUG_VIRTUAL Dave Hansen
2013-04-11 12:37 ` Borislav Petkov
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