Date: Wed, 30 Mar 2022 22:09:00 GMT From: Vincenzo Maffione <vmaffione@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 725c70d8153f - stable/11 - netmap: Fix TOCTOU vulnerability in nmreq_copyin Message-ID: <202203302209.22UM90SB034235@gitrepo.freebsd.org>
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The branch stable/11 has been updated by vmaffione: URL: https://cgit.FreeBSD.org/src/commit/?id=725c70d8153f4bddf95bdd07e2c7b4b9399643f6 commit 725c70d8153f4bddf95bdd07e2c7b4b9399643f6 Author: Vincenzo Maffione <vmaffione@FreeBSD.org> AuthorDate: 2022-03-16 06:58:50 +0000 Commit: Vincenzo Maffione <vmaffione@FreeBSD.org> CommitDate: 2022-03-30 22:08:32 +0000 netmap: Fix TOCTOU vulnerability in nmreq_copyin The total size of the user-provided nmreq was first computed and then trusted during the copyin. This might lead to kernel memory corruption and escape from jails/containers. Reported by: Lucas Leong (@_wmliang_) of Trend Micro Zero Day Initiative Security: CVE-2022-23084 MFC after: 3 days (cherry picked from commit 393729916564ed13f966e09129a24e6931898d12) --- sys/dev/netmap/netmap.c | 46 ++++++++++++++++++---------------------------- 1 file changed, 18 insertions(+), 28 deletions(-) diff --git a/sys/dev/netmap/netmap.c b/sys/dev/netmap/netmap.c index 0c060219ff23..ab2c1b760d6a 100644 --- a/sys/dev/netmap/netmap.c +++ b/sys/dev/netmap/netmap.c @@ -2987,11 +2987,10 @@ nmreq_opt_size_by_type(uint32_t nro_reqtype, uint64_t nro_size) int nmreq_copyin(struct nmreq_header *hdr, int nr_body_is_user) { - size_t rqsz, optsz, bufsz, optbodysz; + size_t rqsz, optsz, bufsz; int error = 0; char *ker = NULL, *p; struct nmreq_option **next, *src; - struct nmreq_option buf; uint64_t *ptrs; if (hdr->nr_reserved) { @@ -3021,32 +3020,14 @@ nmreq_copyin(struct nmreq_header *hdr, int nr_body_is_user) goto out_err; } - bufsz = 2 * sizeof(void *) + rqsz; - optsz = 0; - for (src = (struct nmreq_option *)(uintptr_t)hdr->nr_options; src; - src = (struct nmreq_option *)(uintptr_t)buf.nro_next) - { - error = copyin(src, &buf, sizeof(*src)); - if (error) - goto out_err; - /* Validate nro_size to avoid integer overflow of optsz and bufsz. */ - if (buf.nro_size > NETMAP_REQ_MAXSIZE) { - error = EMSGSIZE; - goto out_err; - } - optsz += sizeof(*src); - optbodysz = nmreq_opt_size_by_type(buf.nro_reqtype, buf.nro_size); - if (optbodysz > NETMAP_REQ_MAXSIZE) { - error = EMSGSIZE; - goto out_err; - } - optsz += optbodysz; - if (rqsz + optsz > NETMAP_REQ_MAXSIZE) { - error = EMSGSIZE; - goto out_err; - } - bufsz += optsz + sizeof(void *); - } + /* + * The buffer size must be large enough to store the request body, + * all the possible options and the additional user pointers + * (2+NETMAP_REQ_OPT_MAX). Note that the maximum size of body plus + * options can not exceed NETMAP_REQ_MAXSIZE; + */ + bufsz = (2 + NETMAP_REQ_OPT_SYNC_KLOOP_MODE + 1) * sizeof(void *) + + NETMAP_REQ_MAXSIZE; ker = nm_os_malloc(bufsz); if (ker == NULL) { @@ -3081,6 +3062,7 @@ nmreq_copyin(struct nmreq_header *hdr, int nr_body_is_user) error = copyin(src, opt, sizeof(*src)); if (error) goto out_restore; + rqsz += sizeof(*src); /* make a copy of the user next pointer */ *ptrs = opt->nro_next; /* overwrite the user pointer with the in-kernel one */ @@ -3096,6 +3078,14 @@ nmreq_copyin(struct nmreq_header *hdr, int nr_body_is_user) /* copy the option body */ optsz = nmreq_opt_size_by_type(opt->nro_reqtype, opt->nro_size); + /* check optsz and nro_size to avoid for possible integer overflows of rqsz */ + if ((optsz > NETMAP_REQ_MAXSIZE) || (opt->nro_size > NETMAP_REQ_MAXSIZE) + || (rqsz + optsz > NETMAP_REQ_MAXSIZE) + || (optsz > 0 && rqsz + optsz <= rqsz)) { + error = EMSGSIZE; + goto out_restore; + } + rqsz += optsz; if (optsz) { /* the option body follows the option header */ error = copyin(src + 1, p, optsz);
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