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Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <000000000000b2585a05fdeb8379@google.com> References: <000000000000b2585a05fdeb8379@google.com> To: syzbot Cc: dhowells@redhat.com, davem@davemloft.net, herbert@gondor.apana.org.au, kuba@kernel.org, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [crypto?] KASAN: slab-out-of-bounds Read in extract_iter_to_sg MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <256754.1686844894.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Thu, 15 Jun 2023 17:01:34 +0100 Message-ID: <256755.1686844894@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.g= it main diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c index 38d2265c77fd..e97abe6055a1 100644 --- a/fs/smb/client/smb2ops.c +++ b/fs/smb/client/smb2ops.c @@ -4333,8 +4333,7 @@ static void *smb2_get_aead_req(struct crypto_aead *t= fm, struct smb_rqst *rqst, } sgtable.orig_nents =3D sgtable.nents; = - rc =3D extract_iter_to_sg(iter, count, &sgtable, - num_sgs - sgtable.nents, 0); + rc =3D extract_iter_to_sg(iter, count, &sgtable, num_sgs, 0); iov_iter_revert(iter, rc); sgtable.orig_nents =3D sgtable.nents; } diff --git a/lib/scatterlist.c b/lib/scatterlist.c index e97d7060329e..6fd20bfc01a4 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -1120,7 +1120,8 @@ static ssize_t extract_user_to_sg(struct iov_iter *i= ter, pages -=3D sg_max; = do { - res =3D iov_iter_extract_pages(iter, &pages, maxsize, sg_max, + res =3D iov_iter_extract_pages(iter, &pages, maxsize, + sg_max - sgtable->nents, extraction_flags, &off); if (res < 0) goto failed; @@ -1129,7 +1130,6 @@ static ssize_t extract_user_to_sg(struct iov_iter *i= ter, maxsize -=3D len; ret +=3D len; npages =3D DIV_ROUND_UP(off + len, PAGE_SIZE); - sg_max -=3D npages; = for (; npages > 0; npages--) { struct page *page =3D *pages; @@ -1142,7 +1142,7 @@ static ssize_t extract_user_to_sg(struct iov_iter *i= ter, len -=3D seg; off =3D 0; } - } while (maxsize > 0 && sg_max > 0); + } while (maxsize > 0 && sgtable->nents < sg_max); = return ret; = @@ -1183,11 +1183,10 @@ static ssize_t extract_bvec_to_sg(struct iov_iter = *iter, sg_set_page(sg, bv[i].bv_page, len, off); sgtable->nents++; sg++; - sg_max--; = ret +=3D len; maxsize -=3D len; - if (maxsize <=3D 0 || sg_max =3D=3D 0) + if (maxsize <=3D 0 || sgtable->nents >=3D sg_max) break; start =3D 0; } @@ -1242,14 +1241,13 @@ static ssize_t extract_kvec_to_sg(struct iov_iter = *iter, sg_set_page(sg, page, len, off); sgtable->nents++; sg++; - sg_max--; = len -=3D seg; kaddr +=3D PAGE_SIZE; off =3D 0; - } while (len > 0 && sg_max > 0); + } while (len > 0 && sgtable->nents < sg_max); = - if (maxsize <=3D 0 || sg_max =3D=3D 0) + if (maxsize <=3D 0 || sgtable->nents >=3D sg_max) break; start =3D 0; } @@ -1294,11 +1292,10 @@ static ssize_t extract_xarray_to_sg(struct iov_ite= r *iter, sg_set_page(sg, folio_page(folio, 0), len, offset); sgtable->nents++; sg++; - sg_max--; = maxsize -=3D len; ret +=3D len; - if (maxsize <=3D 0 || sg_max =3D=3D 0) + if (maxsize <=3D 0 || sgtable->nents >=3D sg_max) break; } = @@ -1318,7 +1315,8 @@ static ssize_t extract_xarray_to_sg(struct iov_iter = *iter, * * Extract the page fragments from the given amount of the source iterato= r and * add them to a scatterlist that refers to all of those bits, to a maxim= um - * addition of @sg_max elements. + * addition of @sg_max elements. @sgtable->nents indicates how many of t= he + * elements are already used. * * The pages referred to by UBUF- and IOVEC-type iterators are extracted = and * pinned; BVEC-, KVEC- and XARRAY-type are extracted but aren't pinned; = PIPE- @@ -1343,6 +1341,11 @@ ssize_t extract_iter_to_sg(struct iov_iter *iter, s= ize_t maxsize, if (maxsize =3D=3D 0) return 0; = + if (WARN_ON_ONCE(sg_max =3D=3D 0)) + return -EIO; + if (WARN_ON_ONCE(sgtable->nents >=3D sg_max)) + return -EIO; + switch (iov_iter_type(iter)) { case ITER_UBUF: case ITER_IOVEC: