Return-Path: linux-nfs-owner@vger.kernel.org Received: from mx1.redhat.com ([209.132.183.28]:14027 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751311Ab2H1OJ3 (ORCPT ); Tue, 28 Aug 2012 10:09:29 -0400 Message-ID: <1346162966.2554.3.camel@localhost> Subject: Re: [PATCH] Avoid array overflow in __nfs4_get_acl_uncached From: Sachin Prabhu To: "Myklebust, Trond" Cc: Linux NFS mailing list Date: Tue, 28 Aug 2012 15:09:26 +0100 In-Reply-To: <4FA345DA4F4AE44899BD2B03EEEC2FA908F69340@SACEXCMBX04-PRD.hq.netapp.com> References: <1345817768-23511-1-git-send-email-sprabhu@redhat.com> <4FA345DA4F4AE44899BD2B03EEEC2FA908F4AF1E@SACEXCMBX01-PRD.hq.netapp.com> <1345843866.2279.6.camel@localhost> <4FA345DA4F4AE44899BD2B03EEEC2FA908F5842F@SACEXCMBX01-PRD.hq.netapp.com> <1345845062.32200.1.camel@localhost> <4FA345DA4F4AE44899BD2B03EEEC2FA908F5859F@SACEXCMBX01-PRD.hq.netapp.com> <1345937503.4943.17.camel@localhost> <4FA345DA4F4AE44899BD2B03EEEC2FA908F69340@SACEXCMBX04-PRD.hq.netapp.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Sender: linux-nfs-owner@vger.kernel.org List-ID: > OK. How about this patch, which applies on top of the one I sent you? > 8<----------------------------------------------------------------- > From 22c9e2475560edda925f971a2a02bac58536414b Mon Sep 17 00:00:00 2001 > From: Trond Myklebust > Date: Sun, 26 Aug 2012 11:44:43 -0700 > Subject: [PATCH] NFSv4: Add buffer overflow checking to nfs4_write_cached_acl > > Currently, the buffer overflow checking is done incorrectly by the > caller. Move the overflow checking into nfs4_write_cached_acl itself > for robustness, and fix the overflow calculation to take into account > the 'pgbase' argument to _copy_from_pages. > > Signed-off-by: Trond Myklebust > --- > fs/nfs/nfs4proc.c | 12 +++++------- > 1 file changed, 5 insertions(+), 7 deletions(-) > > diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c > index 654dc38..af4ebc3 100644 > --- a/fs/nfs/nfs4proc.c > +++ b/fs/nfs/nfs4proc.c > @@ -3734,12 +3734,13 @@ out: > return ret; > } > > -static void nfs4_write_cached_acl(struct inode *inode, struct page **pages, size_t pgbase, size_t acl_len) > +static void nfs4_write_cached_acl(struct inode *inode, struct page **pages, > + size_t srclen, size_t pgbase, size_t acl_len) > { > struct nfs4_cached_acl *acl; > size_t buflen = sizeof(*acl) + acl_len; > > - if (pages && buflen <= PAGE_SIZE) { > + if (buflen <= PAGE_SIZE && srclen <= pgbase + acl_len) { > acl = kmalloc(buflen, GFP_KERNEL); > if (acl == NULL) > goto out; > @@ -3820,11 +3821,8 @@ static ssize_t __nfs4_get_acl_uncached(struct inode *inode, void *buf, size_t bu > goto out_free; > > acl_len = res.acl_len; > - if (acl_len > args.acl_len) > - nfs4_write_cached_acl(inode, NULL, 0, acl_len); > - else > - nfs4_write_cached_acl(inode, pages, res.acl_data_offset, > - acl_len); > + nfs4_write_cached_acl(inode, pages, args.acl_len, > + res.acl_data_offset, res.acl_len); > if (buf) { > ret = -ERANGE; > if (acl_len > buflen) > -- > 1.7.11.4 I encountered 2 problems. 1) The if condition should be srclen >= pgbase + acl_len 2) There is a second _copy_from_pages which copies to the the acl to the passed buffer in __nfs4_get_acl_uncached(). I've attached a patch below. ----- >From ec84527625b3847a0623410d532253dd919e119a Mon Sep 17 00:00:00 2001 From: Sachin Prabhu Date: Tue, 28 Aug 2012 15:01:13 +0100 Subject: [PATCH] NFSv4: Check for buffer overflow in __nfs4_get_acl_uncached Check for buffer overflow in __nfs4_get_acl_uncached when using _copy_from_pages to copy to the buffer passed in the argument. Also fix if condition in nfs4_write_cached_acl() from the previous post. Signed-off-by: Sachin Prabhu --- fs/nfs/nfs4proc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index 580b0b1..cb8748d 100644 --- a/fs/nfs/nfs4proc.c +++ b/fs/nfs/nfs4proc.c @@ -3740,7 +3740,7 @@ static void nfs4_write_cached_acl(struct inode *inode, struct page **pages, struct nfs4_cached_acl *acl; size_t buflen = sizeof(*acl) + acl_len; - if (buflen <= PAGE_SIZE && srclen <= pgbase + acl_len) { + if (buflen <= PAGE_SIZE && srclen >= pgbase + acl_len) { acl = kmalloc(buflen, GFP_KERNEL); if (acl == NULL) goto out; @@ -3825,7 +3825,7 @@ static ssize_t __nfs4_get_acl_uncached(struct inode *inode, void *buf, size_t bu res.acl_data_offset, res.acl_len); if (buf) { ret = -ERANGE; - if (acl_len > buflen) + if (acl_len > buflen || args.acl_len < res.acl_data_offset + res.acl_len) goto out_free; _copy_from_pages(buf, pages, res.acl_data_offset, acl_len); -- 1.7.11.4