[PATCH][UBIFS] Fix mount oops with wrong name

[Adrian Hunter]

Kyungmin Park wrote:
> Also remove white space
> 
> / # mount -t ubifs ubiubifs /tmp
> Unable to handle kernel NULL pointer dereference at virtual address 00000000
> pgd = c783c000
> [00000000] *pgd=8786d031, *pte=00000000, *ppte=00000000
> Internal error: Oops: 17 [#1]
> Modules linked in: ubifs ubi
> CPU: 0    Not tainted  (2.6.23 #15)
> PC is at ubi_get_volume_info+0xc/0x84 [ubi]
> LR is at ubifs_get_sb+0x4c0/0xfe4 [ubifs]
> pc : [<bf0038c8>]    lr : [<bf017f58>]    psr: 60000013
> sp : c783bcfc  ip : c783bd10  fp : c783bd0c
> r10: bf03dc70  r9 : c7e1d000  r8 : c7e1d37c
> r7 : c7e1d374  r6 : c7e1d0a0  r5 : c02b0534  r4 : 00000000
> r3 : 00000002  r2 : 00000075  r1 : c7e1d330  r0 : 00000000
> Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
> Control: 00c5387f  Table: 8783c000  DAC: 00000015
> Process mount (pid: 283, stack limit = 0xc783a258)
> Stack: (0xc783bcfc to 0xc783c000)
> Backtrace:
> [<bf0038bc>] (ubi_get_volume_info+0x0/0x84 [ubi]) from [<bf017f58>] (ubifs_get_)
>  r4:00000000
> [<bf017a98>] (ubifs_get_sb+0x0/0xfe4 [ubifs]) from [<c0083c10>] (vfs_kern_mount)
> [<c0083bb0>] (vfs_kern_mount+0x0/0xc0) from [<c0083cb8>] (do_kern_mount+0x48/0x)
>  r8:c7f4b000 r7:bf03d66c r6:c7899000 r5:c78ee000 r4:00000000
> [<c0083c70>] (do_kern_mount+0x0/0xf4) from [<c0099d24>] (do_mount+0x604/0x640)
>  r8:00000000 r7:00000000 r6:c7f97000 r5:c78ee000 r4:00000000
> [<c0099720>] (do_mount+0x0/0x640) from [<c009a078>] (sys_mount+0xa4/0xec)
> [<c0099fd4>] (sys_mount+0x0/0xec) from [<c001ee40>] (ret_fast_syscall+0x0/0x2c)
>  r7:00000015 r6:00000000 r5:c0ed0000 r4:00084050
> Code: bf012734 e1a0c00d e92dd810 e24cb004 (e5900000)
> 
> Signed-off-by: Kyungmin Park <kyungmin.park at samsung.com>
> ---
> diff --git a/fs/ubifs/build.c b/fs/ubifs/build.c
> index 6609e49..82b8f70 100644
> --- a/fs/ubifs/build.c
> +++ b/fs/ubifs/build.c
> @@ -323,7 +323,7 @@ static int alloc_wbufs(struct ubifs_info *c)
>  		if (err)
>  			return err;
>  
> -		c->jheads[i].wbuf.sync_callback =  &bud_wbuf_callback;
> +		c->jheads[i].wbuf.sync_callback = &bud_wbuf_callback;
>  		c->jheads[i].wbuf.jhead = i;
>  	}
>  
> @@ -962,10 +962,12 @@ static int open_ubi(struct ubifs_info *c, const char *name, int mode)
>  			c->ubi = ubi_open_volume_nm(dev, ++endptr, mode);
>  			if (IS_ERR(c->ubi))
>  				return PTR_ERR(c->ubi);
> -		} else
> -			return -EINVAL;
> +		}
>  	}
>  
> +	if (!c->ubi)
> +		return -EINVAL;
> +
>  	ubi_get_volume_info(c->ubi, &c->vi);
>  	ubi_get_device_info(c->vi.ubi_num, &c->di);
>  	return 0;

Thank you