fat_encode_fh() can fetch an invalid i_pos value on systems
where 64-bit accesses are not atomic. Make it use the same
accessor as the rest of the FAT code.
Signed-off-by: Steven J. Magnani <[email protected]>
---
diff -uprN linux-3.5-rc4/fs/fat/inode.c new/fs/fat/inode.c
--- linux-3.5-rc4/fs/fat/inode.c 2012-06-29 11:20:12.781348652 -0500
+++ new/fs/fat/inode.c 2012-06-29 11:25:29.484713183 -0500
@@ -738,22 +738,22 @@ static int
fat_encode_fh(struct inode *inode, __u32 *fh, int *lenp, struct inode *parent)
{
int len = *lenp;
- u32 ipos_h, ipos_m, ipos_l;
+ struct super_block *sb = inode->i_sb;
+ struct msdos_sb_info *sbi = MSDOS_SB(sb);
+ loff_t i_pos;
if (len < 5) {
*lenp = 5;
return 255; /* no room */
}
- ipos_h = MSDOS_I(inode)->i_pos >> 8;
- ipos_m = (MSDOS_I(inode)->i_pos & 0xf0) << 24;
- ipos_l = (MSDOS_I(inode)->i_pos & 0x0f) << 28;
+ i_pos = fat_i_pos_read(sbi, inode);
*lenp = 5;
fh[0] = inode->i_ino;
fh[1] = inode->i_generation;
- fh[2] = ipos_h;
- fh[3] = ipos_m | MSDOS_I(inode)->i_logstart;
- fh[4] = ipos_l;
+ fh[2] = i_pos >> 8;
+ fh[3] = ((i_pos & 0xf0) << 24) | MSDOS_I(inode)->i_logstart;
+ fh[4] = (i_pos & 0x0f) << 28;
if (parent)
fh[4] |= MSDOS_I(parent)->i_logstart;
return 3;
"Steven J. Magnani" <[email protected]> writes:
> fat_encode_fh() can fetch an invalid i_pos value on systems
> where 64-bit accesses are not atomic. Make it use the same
> accessor as the rest of the FAT code.
>
> Signed-off-by: Steven J. Magnani <[email protected]>
> ---
> diff -uprN linux-3.5-rc4/fs/fat/inode.c new/fs/fat/inode.c
> --- linux-3.5-rc4/fs/fat/inode.c 2012-06-29 11:20:12.781348652 -0500
> +++ new/fs/fat/inode.c 2012-06-29 11:25:29.484713183 -0500
> @@ -738,22 +738,22 @@ static int
> fat_encode_fh(struct inode *inode, __u32 *fh, int *lenp, struct inode *parent)
> {
> int len = *lenp;
> - u32 ipos_h, ipos_m, ipos_l;
> + struct super_block *sb = inode->i_sb;
> + struct msdos_sb_info *sbi = MSDOS_SB(sb);
sb seems to be unused. So, we can just
struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
true? Otherwise, ack.
Acked-by: OGAWA Hirofumi <[email protected]>
Just curious, this happened on the real system? I recently heard about
NFS issue.
Thanks.
> + loff_t i_pos;
>
> if (len < 5) {
> *lenp = 5;
> return 255; /* no room */
> }
>
> - ipos_h = MSDOS_I(inode)->i_pos >> 8;
> - ipos_m = (MSDOS_I(inode)->i_pos & 0xf0) << 24;
> - ipos_l = (MSDOS_I(inode)->i_pos & 0x0f) << 28;
> + i_pos = fat_i_pos_read(sbi, inode);
> *lenp = 5;
> fh[0] = inode->i_ino;
> fh[1] = inode->i_generation;
> - fh[2] = ipos_h;
> - fh[3] = ipos_m | MSDOS_I(inode)->i_logstart;
> - fh[4] = ipos_l;
> + fh[2] = i_pos >> 8;
> + fh[3] = ((i_pos & 0xf0) << 24) | MSDOS_I(inode)->i_logstart;
> + fh[4] = (i_pos & 0x0f) << 28;
> if (parent)
> fh[4] |= MSDOS_I(parent)->i_logstart;
> return 3;
>
--
OGAWA Hirofumi <[email protected]>
On Sat, 2012-06-30 at 03:06 +0900, OGAWA Hirofumi wrote:
> "Steven J. Magnani" <[email protected]> writes:
>
> > fat_encode_fh() can fetch an invalid i_pos value on systems
> > where 64-bit accesses are not atomic. Make it use the same
> > accessor as the rest of the FAT code.
> >
> > Signed-off-by: Steven J. Magnani <[email protected]>
> > ---
> > diff -uprN linux-3.5-rc4/fs/fat/inode.c new/fs/fat/inode.c
> > --- linux-3.5-rc4/fs/fat/inode.c 2012-06-29 11:20:12.781348652 -0500
> > +++ new/fs/fat/inode.c 2012-06-29 11:25:29.484713183 -0500
> > @@ -738,22 +738,22 @@ static int
> > fat_encode_fh(struct inode *inode, __u32 *fh, int *lenp, struct inode *parent)
> > {
> > int len = *lenp;
> > - u32 ipos_h, ipos_m, ipos_l;
> > + struct super_block *sb = inode->i_sb;
> > + struct msdos_sb_info *sbi = MSDOS_SB(sb);
>
> sb seems to be unused. So, we can just
>
> struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
>
> true? Otherwise, ack.
OK, I'll repost with that change.
>
> Acked-by: OGAWA Hirofumi <[email protected]>
>
> Just curious, this happened on the real system? I recently heard about
> NFS issue.
Not that I'm aware of. Can you point me to any discussion of the NFS
issue? I've spent a lot of time recently studying the FAT NFS
implementation and come to the conclusion that it is extremely
vulnerable to inode eviction. More to follow...
Regards,
Steve
"Steven J. Magnani" <[email protected]> writes:
>> Just curious, this happened on the real system? I recently heard about
>> NFS issue.
> Not that I'm aware of. Can you point me to any discussion of the NFS
> issue? I've spent a lot of time recently studying the FAT NFS
> implementation and come to the conclusion that it is extremely
> vulnerable to inode eviction. More to follow...
It is true, I also know NFS support of FAT is broken, but I'm not sure
if it was read-only. Sorry, recent report was by private email, not
public.
--
OGAWA Hirofumi <[email protected]>