[PATCH] [RESEND] jffs2: bugfix of summary length

[PATCH] [RESEND] jffs2: bugfix of summary length

[chenjie6]

From: Chen Jie <chenjie6@huawei.com>

sm->offset maybe wrong but magic maybe right, the offset 
do not have CRC.

------------[ cut here ]------------
Badness at c00c7580 [verbose debug info unavailable]
NIP: c00c7580 LR: c00c718c CTR: 00000014
REGS: df07bb40 TRAP: 0700   Not tainted  (2.6.34.13-WR4.3.0.0_standard)
MSR: 00029000 <EE,ME,CE>  CR: 22084f84  XER: 00000000
TASK = df84d6e0[908] 'mount' THREAD: df07a000
GPR00: 00000001 df07bbf0 df84d6e0 00000000 00000001 00000000 df07bb58 00000041
GPR08: 00000041 c0638860 00000000 00000010 22084f88 100636c8 df814ff8 00000000
GPR16: df84d6e0 dfa558cc c05adb90 00000048 c0452d30 00000000 000240d0 000040d0
GPR24: 00000014 c05ae734 c05be2e0 00000000 00000001 00000000 00000000 c05ae730
NIP [c00c7580] __alloc_pages_nodemask+0x4d0/0x638
LR [c00c718c] __alloc_pages_nodemask+0xdc/0x638
Call Trace:
[df07bbf0] [c00c718c] __alloc_pages_nodemask+0xdc/0x638 (unreliable)
[df07bc90] [c00c7708] __get_free_pages+0x20/0x48
[df07bca0] [c00f4a40] __kmalloc+0x15c/0x1ec
[df07bcd0] [c01fc880] jffs2_scan_medium+0xa58/0x14d0
[df07bd70] [c01ff38c] jffs2_do_mount_fs+0x1f4/0x6b4
[df07bdb0] [c020144c] jffs2_do_fill_super+0xa8/0x260
[df07bdd0] [c020230c] jffs2_fill_super+0x104/0x184
[df07be00] [c0335814] get_sb_mtd_aux+0x9c/0xec
[df07be20] [c033596c] get_sb_mtd+0x84/0x1e8
[df07be60] [c0201ed0] jffs2_get_sb+0x1c/0x2c
[df07be70] [c0103898] vfs_kern_mount+0x78/0x1e8
[df07bea0] [c0103a58] do_kern_mount+0x40/0x100
[df07bec0] [c011fe90] do_mount+0x240/0x890
[df07bf10] [c0120570] sys_mount+0x90/0xd8
[df07bf40] [c00110d8] ret_from_syscall+0x0/0x4
--- Exception: c01 at 0xff61a34
    LR = 0x100135f0
Instruction dump:
38800005 38600000 48010f41 4bfffe1c 4bfc2d15 4bfffe8c 72e90200 4082fc28
3d20c064 39298860 8809000d 68000001 <0f000000> 2f800000 419efc0c 38000001
mount: mounting /dev/mtdblock3 on /common failed: Input/output error


Cc: <stable@vger.kernel.org>
Signed-off-by: Chen Jie <chenjie6@huawei.com>

---
 fs/jffs2/scan.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/jffs2/scan.c b/fs/jffs2/scan.c
index 7654e87..ba978363 100644
--- a/fs/jffs2/scan.c
+++ b/fs/jffs2/scan.c
@@ -509,6 +509,10 @@ static int jffs2_scan_eraseblock (struct jffs2_sb_info *c, struct jffs2_eraseblo
 			if (je32_to_cpu(sm->magic) == JFFS2_SUM_MAGIC) {
 				sumlen = c->sector_size - je32_to_cpu(sm->offset);
 				sumptr = buf + buf_size - sumlen;
+
+				/* sm->offset maybe wrong but MAGIC maybe right */
+				if (sumlen > c->sector_size)
+					goto full_scan;
 
 				/* Now, make sure the summary itself is available */
 				if (sumlen > buf_size) {
@@ -544,6 +548,7 @@ static int jffs2_scan_eraseblock (struct jffs2_sb_info *c, struct jffs2_eraseblo
 		}
 	}
 
+full_scan:
 	buf_ofs = jeb->offset;
 
 	if (!buf_size) {
-- 
1.8.0

Re: [PATCH] [RESEND] jffs2: bugfix of summary length

[Andrew Morton]

On Thu, 18 Dec 2014 19:04:48 +0800 <chenjie6@huawei.com> wrote:

> From: Chen Jie <chenjie6@huawei.com>
> 
> sm->offset maybe wrong but magic maybe right, the offset 
> do not have CRC.

How does this situation arise?  Corrupted device contents?

[PATCH] [RESEND] jffs2: bugfix of summary length

[chenjie6]

From: chenjie <chenjie6@huawei.com>

When power is off, the magic of summary is writed but the length not 
so the length is 0xffffffff, sumlen maybe very large. 
The kmalloc() failed  and mount failed.
	
Cc: <stable@vger.kernel.org>
Signed-off-by: Chen Jie <chenjie6@huawei.com>
---
 fs/jffs2/scan.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/jffs2/scan.c b/fs/jffs2/scan.c
index 7654e87..6187e56 100644
--- a/fs/jffs2/scan.c
+++ b/fs/jffs2/scan.c
@@ -510,6 +510,9 @@ static int jffs2_scan_eraseblock (struct jffs2_sb_info *c, struct jffs2_eraseblo
 				sumlen = c->sector_size - je32_to_cpu(sm->offset);
 				sumptr = buf + buf_size - sumlen;
 
+				if (sumlen > c->sector_size)
+					goto full_scan;
+
 				/* Now, make sure the summary itself is available */
 				if (sumlen > buf_size) {
 					/* Need to kmalloc for this. */
@@ -544,6 +547,7 @@ static int jffs2_scan_eraseblock (struct jffs2_sb_info *c, struct jffs2_eraseblo
 		}
 	}
 
+full_scan:
 	buf_ofs = jeb->offset;
 
 	if (!buf_size) {
-- 
1.8.0

Re: [PATCH] [RESEND] jffs2: bugfix of summary length

[Brian Norris]

On Fri, Dec 12, 2014 at 03:03:44AM +0800, chenjie6@huawei.com wrote:
> From: chenjie <chenjie6@huawei.com>

Can you put your real name here? You have it (presumably) correct in the
sign-off.

> 
> When power is off, the magic of summary is writed but the length not 
> so the length is 0xffffffff, sumlen maybe very large. 
> The kmalloc() failed  and mount failed.

Did you catch this during power-cut testing? On real hardware or
emulation?

> Cc: <stable@vger.kernel.org>
> Signed-off-by: Chen Jie <chenjie6@huawei.com>
> ---
>  fs/jffs2/scan.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/fs/jffs2/scan.c b/fs/jffs2/scan.c
> index 7654e87..6187e56 100644
> --- a/fs/jffs2/scan.c
> +++ b/fs/jffs2/scan.c
> @@ -510,6 +510,9 @@ static int jffs2_scan_eraseblock (struct jffs2_sb_info *c, struct jffs2_eraseblo
>  				sumlen = c->sector_size - je32_to_cpu(sm->offset);
>  				sumptr = buf + buf_size - sumlen;
>  
> +				if (sumlen > c->sector_size)
> +					goto full_scan;

Can you add a comment above this to suggest why this would occur?

> +
>  				/* Now, make sure the summary itself is available */
>  				if (sumlen > buf_size) {
>  					/* Need to kmalloc for this. */
> @@ -544,6 +547,7 @@ static int jffs2_scan_eraseblock (struct jffs2_sb_info *c, struct jffs2_eraseblo
>  		}
>  	}
>  
> +full_scan:
>  	buf_ofs = jeb->offset;
>  
>  	if (!buf_size) {

I'll admit, I'm not much of a JFFS2 developer. I'll have to take a
little closer look at this before I'm comfortable taking this, esp. with
the -stable tag.

Brian