From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.bootlin.com ([62.4.15.54]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1fVaBJ-0004RY-Pl for linux-mtd@lists.infradead.org; Wed, 20 Jun 2018 10:17:43 +0000 Date: Wed, 20 Jun 2018 12:17:20 +0200 From: Boris Brezillon To: Richard Weinberger Cc: linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 01/14] ubi: fastmap: Read PEB numbers more carefully Message-ID: <20180620121720.22ad75c9@bbrezillon> In-Reply-To: <20180613212344.11608-2-richard@nod.at> References: <20180613212344.11608-1-richard@nod.at> <20180613212344.11608-2-richard@nod.at> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 13 Jun 2018 23:23:31 +0200 Richard Weinberger wrote: > PEB numbers can be used as indices, make sure that they > are within bounds. > > Signed-off-by: Richard Weinberger > --- > drivers/mtd/ubi/fastmap.c | 71 ++++++++++++++++++++++++++++++++++++++--------- > 1 file changed, 58 insertions(+), 13 deletions(-) > > diff --git a/drivers/mtd/ubi/fastmap.c b/drivers/mtd/ubi/fastmap.c > index 462526a10537..768fa8a76867 100644 > --- a/drivers/mtd/ubi/fastmap.c > +++ b/drivers/mtd/ubi/fastmap.c > @@ -101,6 +101,29 @@ size_t ubi_calc_fm_size(struct ubi_device *ubi) > return roundup(size, ubi->leb_size); > } > > +static bool read_pnum(struct ubi_device *ubi, struct ubi_attach_info *ai, > + __be32 pnum, int *out_pnum) Why not returning an int here, with negative values meaning that pnum is invalid and positive values encoding the actual PEB number? Also, I think check_pnum(), validate_pnum() or decode_pnum() would be better names than read_pnum(). > +{ > + int ret = true; > + int max_pnum = ubi->peb_count; > + > + pnum = be32_to_cpu(pnum); > + if (pnum == UBI_UNKNOWN) { > + *out_pnum = pnum; > + goto out; > + } > + > + if (pnum < 0 || pnum >= max_pnum) { > + ubi_err(ubi, "fastmap references PEB out of range: %i", pnum); > + ret = false; > + goto out; > + } else { > + *out_pnum = pnum; > + } > + > +out: > + return ret; > +} > > /** > * new_fm_vhdr - allocate a new volume header for fastmap usage. > @@ -438,7 +461,10 @@ static int scan_pool(struct ubi_device *ubi, struct ubi_attach_info *ai, > int scrub = 0; > int image_seq; > > - pnum = be32_to_cpu(pebs[i]); > + if (!read_pnum(ubi, ai, pebs[i], &pnum)) { > + ret = UBI_BAD_FASTMAP; > + goto out; > + } > > if (ubi_io_is_bad(ubi, pnum)) { > ubi_err(ubi, "bad PEB in fastmap pool!"); > @@ -565,7 +591,7 @@ static int ubi_attach_fastmap(struct ubi_device *ubi, > struct ubi_fm_ec *fmec; > struct ubi_fm_volhdr *fmvhdr; > struct ubi_fm_eba *fm_eba; > - int ret, i, j, pool_size, wl_pool_size; > + int ret, i, j, pool_size, wl_pool_size, pnum; > size_t fm_pos = 0, fm_size = ubi->fm_size; > unsigned long long max_sqnum = 0; > void *fm_raw = ubi->fm_buf; > @@ -647,8 +673,10 @@ static int ubi_attach_fastmap(struct ubi_device *ubi, > if (fm_pos >= fm_size) > goto fail_bad; > > - add_aeb(ai, &ai->free, be32_to_cpu(fmec->pnum), > - be32_to_cpu(fmec->ec), 0); > + if (!read_pnum(ubi, ai, fmec->pnum, &pnum)) > + goto fail_bad; > + > + add_aeb(ai, &ai->free, pnum, be32_to_cpu(fmec->ec), 0); > } > > /* read EC values from used list */ > @@ -658,8 +686,10 @@ static int ubi_attach_fastmap(struct ubi_device *ubi, > if (fm_pos >= fm_size) > goto fail_bad; > > - add_aeb(ai, &used, be32_to_cpu(fmec->pnum), > - be32_to_cpu(fmec->ec), 0); > + if (!read_pnum(ubi, ai, fmec->pnum, &pnum)) > + goto fail_bad; > + > + add_aeb(ai, &used, pnum, be32_to_cpu(fmec->ec), 0); > } > > /* read EC values from scrub list */ > @@ -669,8 +699,10 @@ static int ubi_attach_fastmap(struct ubi_device *ubi, > if (fm_pos >= fm_size) > goto fail_bad; > > - add_aeb(ai, &used, be32_to_cpu(fmec->pnum), > - be32_to_cpu(fmec->ec), 1); > + if (!read_pnum(ubi, ai, fmec->pnum, &pnum)) > + goto fail_bad; > + > + add_aeb(ai, &used, pnum, be32_to_cpu(fmec->ec), 1); > } > > /* read EC values from erase list */ > @@ -680,8 +712,10 @@ static int ubi_attach_fastmap(struct ubi_device *ubi, > if (fm_pos >= fm_size) > goto fail_bad; > > - add_aeb(ai, &ai->erase, be32_to_cpu(fmec->pnum), > - be32_to_cpu(fmec->ec), 1); > + if (!read_pnum(ubi, ai, fmec->pnum, &pnum)) > + goto fail_bad; > + > + add_aeb(ai, &ai->erase, pnum, be32_to_cpu(fmec->ec), 1); > } > > ai->mean_ec = div_u64(ai->ec_sum, ai->ec_count); > @@ -731,7 +765,8 @@ static int ubi_attach_fastmap(struct ubi_device *ubi, > } > > for (j = 0; j < be32_to_cpu(fm_eba->reserved_pebs); j++) { > - int pnum = be32_to_cpu(fm_eba->pnum[j]); > + if (!read_pnum(ubi, ai, fm_eba->pnum[j], &pnum)) > + goto fail_bad; > > if (pnum < 0) > continue; > @@ -954,7 +989,10 @@ int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info *ai, > for (i = 0; i < used_blocks; i++) { > int image_seq; > > - pnum = be32_to_cpu(fmsb->block_loc[i]); > + if (!read_pnum(ubi, ai, fmsb->block_loc[i], &pnum)) { > + ret = UBI_BAD_FASTMAP; > + goto free_hdr; > + } > > if (ubi_io_is_bad(ubi, pnum)) { > ret = UBI_BAD_FASTMAP; > @@ -1068,7 +1106,14 @@ int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info *ai, > goto free_hdr; > } > > - e->pnum = be32_to_cpu(fmsb2->block_loc[i]); > + if (!read_pnum(ubi, ai, fmsb2->block_loc[i], &e->pnum)) { > + while (i--) > + kmem_cache_free(ubi_wl_entry_slab, fm->e[i]); > + > + ret = -ENOMEM; > + goto free_hdr; > + } > + > e->ec = be32_to_cpu(fmsb2->block_ec[i]); > fm->e[i] = e; > }