On Thursday 19 May 2022 07:01:19 Stefan Roese wrote:
> On 17.05.22 22:45, Pali Rohár wrote:
> > Commit b1a14f8a1c2e ("UBIFS: Change ubifsload to not read beyond the
> > requested size") added optimization to do not read more bytes than it is
> > really needed. But this commit introduced incorrect handling of the hole at
> > the end of file. This logic cause U-Boot to crash or lockup when trying to
> > read from the ubifs filesystem.
> >
> > When read_block() call returns -ENOENT error (not an error, but the hole)
> > then dn-> structure is not filled and contain garbage. So using of dn->size
> > for memcpy() argument cause that U-Boot tries to copy unspecified amount of
> > bytes from possible unmapped memory. Which randomly cause lockup of P2020
> > CPU.
> >
> > Fix this issue by copying UBIFS_BLOCK_SIZE bytes from read buffer when
> > dn->size is not available. UBIFS_BLOCK_SIZE is the size of the buffer
> > itself and read_block() fills buffer by zeros when it returns -ENOENT.
> >
> > This patch fixes ubifsload on P2020.
> >
> > Fixes: b1a14f8a1c2e ("UBIFS: Change ubifsload to not read beyond the
> > requested size")
> > Signed-off-by: Pali Rohár <p...@kernel.org>
>
> Reviewed-by: Stefan Roese <s...@denx.de>
>
> > ---
> >
> > Stefan, could you please look at this patch? Mentioned commit was
> > introduced by you more than 11 years ago. I'm surprised that nobody hit
> > this issue yet, but it looks like older U-Boot versions somehow filled
> > small garbage number into dn->size and did not cause U-Boot
> > lockup/crash.
>
> So long ago. I don't really remember the details. IIRC, I introduced the
> UBIFS support for some MIPS based board at that time. My best assumption
> is, that UBIFS is rarely used in U-Boot in general.
It is used on Turris 1.x (powerpc).
> Thanks,
> Stefan
>
> > ---
> > fs/ubifs/ubifs.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/fs/ubifs/ubifs.c b/fs/ubifs/ubifs.c
> > index d6be5c947d7e..d3026e310168 100644
> > --- a/fs/ubifs/ubifs.c
> > +++ b/fs/ubifs/ubifs.c
> > @@ -771,40 +771,42 @@ static int do_readpage(struct ubifs_info *c, struct
> > inode *inode,
> > buff = malloc_cache_aligned(UBIFS_BLOCK_SIZE);
> > if (!buff) {
> > printf("%s: Error, malloc fails!\n",
> > __func__);
> > err = -ENOMEM;
> > break;
> > }
> > /* Read block-size into temp buffer */
> > ret = read_block(inode, buff, block, dn);
> > if (ret) {
> > err = ret;
> > if (err != -ENOENT) {
> > free(buff);
> > break;
> > }
> > }
> > if (last_block_size)
> > dlen = last_block_size;
> > + else if (ret)
> > + dlen = UBIFS_BLOCK_SIZE;
> > else
> > dlen = le32_to_cpu(dn->size);
> > /* Now copy required size back to dest */
> > memcpy(addr, buff, dlen);
> > free(buff);
> > } else {
> > ret = read_block(inode, addr, block, dn);
> > if (ret) {
> > err = ret;
> > if (err != -ENOENT)
> > break;
> > }
> > }
> > }
> > if (++i >= UBIFS_BLOCKS_PER_PAGE)
> > break;
> > block += 1;
> > addr += UBIFS_BLOCK_SIZE;
>
> Viele Grüße,
> Stefan Roese
>
> --
> DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
> HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
> Phone: (+49)-8142-66989-51 Fax: (+49)-8142-66989-80 Email: s...@denx.de
