Re: Crash (ext3 ) during 2.6.29-rc6 boot
From: Mark Nelson
Date: Wed Feb 25 2009 - 07:08:59 EST
On Wed, 25 Feb 2009 08:50:46 pm Geert Uytterhoeven wrote:
> On Wed, 25 Feb 2009, Mark Nelson wrote:
> > On Tue, 24 Feb 2009 05:38:37 pm Sachin P. Sant wrote:
> > > Jan Kara wrote:
> > > > Hmm, OK. But then I'm not sure how that can happen. Obviously, memcpy
> > > > somehow got beyond end of the page referenced by bh->b_data. So it means
> > > > that le16_to_cpu(entry->e_value_offs) + size > page_size. But
> > > > ext3_xattr_find_entry() calls ext3_xattr_check_entry() which in
> > > > particular checks whether e_value_offs + e_value_size isn't greater than
> > > > bh->b_size. So I see no way how memcpy can get beyond end of the page.
> > > > Sachin, is the problem reproducible? If yes, can you send us contents
> > > >
> > > Yes, i am able to recreate this problem easily. As i had mentioned if the
> > > earlier kernel is booted with selinux enabled and then 2.6.29-rc6 is booted
> > > i get this crash. But if i specify selinux=0 at command line, 2.6.29-rc6 boots
> > > without any problem.
> >
> > Hi Sanchin and Geert,
> >
> > Does the patch below fix the problems you're seeing? If it does I'll send
> > a properly written up and formatted patch to linuxppc-dev (as well as
> > another one to fix the same problem in copy_tofrom_user()).
>
> Unfortunately not, now it crashes while accessing the memory pointed to by
> GPR16, in
>
> NIP: copy_page_range+x0608/0x628
> LR: dup_mm+0x2e4/0x428
> Trace: debug_table+0xcc70/0x1afe0 (unreliable)
> dup_mm+0x2e4/0x428
> copy_process+0x86c/0xf9c
> do_fork+0x188/0x39c
> sys_clone+0x58/0x70
> ppc_clone+0x8/0xc
>
> However, after reverting 25d6e2d7c58ddc4a3b614fc5381591c0cfe66556, I still see
> similar problems as above (crash in copy_page_range()).
> Which makes me think that
> 1. Your new patch fixes the problem introduced by 25d6e2d7,
> 2. There's still another issue than the one introduced by 25d6e2d7.
Does the following patch fix the errors you're seeing? (it applies the
same fix as the previous patch but this time to copy_tofrom_user, which
I updated in a4e22f02f5b6518c1484faea1f88d81802b9feac)
Thanks!
Mark
---
arch/powerpc/lib/copyuser_64.S | 38 +++++++++++++++++++++++++++++++-------
1 file changed, 31 insertions(+), 7 deletions(-)
Index: upstream/arch/powerpc/lib/copyuser_64.S
===================================================================
--- upstream.orig/arch/powerpc/lib/copyuser_64.S
+++ upstream/arch/powerpc/lib/copyuser_64.S
@@ -62,18 +62,19 @@ END_FTR_SECTION_IFCLR(CPU_FTR_UNALIGNED_
72: std r8,8(r3)
beq+ 3f
addi r3,r3,16
-23: ld r9,8(r4)
.Ldo_tail:
bf cr7*4+1,1f
- rotldi r9,r9,32
+23: lwz r9,8(r4)
+ addi r4,r4,4
73: stw r9,0(r3)
addi r3,r3,4
1: bf cr7*4+2,2f
- rotldi r9,r9,16
+44: lhz r9,8(r4)
+ addi r4,r4,2
74: sth r9,0(r3)
addi r3,r3,2
2: bf cr7*4+3,3f
- rotldi r9,r9,8
+45: lbz r9,8(r4)
75: stb r9,0(r3)
3: li r3,0
blr
@@ -141,11 +142,24 @@ END_FTR_SECTION_IFCLR(CPU_FTR_UNALIGNED_
6: cmpwi cr1,r5,8
addi r3,r3,32
sld r9,r9,r10
- ble cr1,.Ldo_tail
+ ble cr1,7f
34: ld r0,8(r4)
srd r7,r0,r11
or r9,r7,r9
- b .Ldo_tail
+7:
+ bf cr7*4+1,1f
+ rotldi r9,r9,32
+94: stw r9,0(r3)
+ addi r3,r3,4
+1: bf cr7*4+2,2f
+ rotldi r9,r9,16
+95: sth r9,0(r3)
+ addi r3,r3,2
+2: bf cr7*4+3,3f
+ rotldi r9,r9,8
+96: stb r9,0(r3)
+3: li r3,0
+ blr
.Ldst_unaligned:
PPC_MTOCRF 0x01,r6 /* put #bytes to 8B bdry into cr7 */
@@ -218,7 +232,6 @@ END_FTR_SECTION_IFCLR(CPU_FTR_UNALIGNED_
121:
132:
addi r3,r3,8
-123:
134:
135:
138:
@@ -226,6 +239,9 @@ END_FTR_SECTION_IFCLR(CPU_FTR_UNALIGNED_
140:
141:
142:
+123:
+144:
+145:
/*
* here we have had a fault on a load and r3 points to the first
@@ -309,6 +325,9 @@ END_FTR_SECTION_IFCLR(CPU_FTR_UNALIGNED_
187:
188:
189:
+194:
+195:
+196:
1:
ld r6,-24(r1)
ld r5,-8(r1)
@@ -329,7 +348,9 @@ END_FTR_SECTION_IFCLR(CPU_FTR_UNALIGNED_
.llong 72b,172b
.llong 23b,123b
.llong 73b,173b
+ .llong 44b,144b
.llong 74b,174b
+ .llong 45b,145b
.llong 75b,175b
.llong 24b,124b
.llong 25b,125b
@@ -347,6 +368,9 @@ END_FTR_SECTION_IFCLR(CPU_FTR_UNALIGNED_
.llong 79b,179b
.llong 80b,180b
.llong 34b,134b
+ .llong 94b,194b
+ .llong 95b,195b
+ .llong 96b,196b
.llong 35b,135b
.llong 81b,181b
.llong 36b,136b
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/