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[2001:470:7:582::2]) by smtp.gmail.com with ESMTPSA id g1-20020a379d01000000b0069fc13ce1fesm13326qke.47.2022.05.20.10.11.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 May 2022 10:11:28 -0700 (PDT) Date: Fri, 20 May 2022 13:11:25 -0400 From: Jan Harkes To: Kees Cook Cc: linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH] fs/coda: Do not use partially allocated struct Message-ID: <20220520171125.7u7q4ih5udkykv6b@cs.cmu.edu> References: <20220520165922.2140450-1-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220520165922.2140450-1-keescook@chromium.org> User-Agent: NeoMutt/20180716 Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org Looks good to me. The old code was trying to be too smart for its own good and the type gets lost by the uc_data = (void *) cast anyway. Jan On Fri, May 20, 2022 at 09:59:22AM -0700, Kees Cook wrote: > GCC 12 does not like seeing a partially allocated structure being used, > especially when a pointer is being passed out of function scope. Since > only the struct coda_in_hdr member of union inputArgs is being allocated > and used, just replace union inputArgs with struct coda_in_hdr. > > ../fs/coda/upcall.c: In function 'coda_upcall': > ../fs/coda/upcall.c:801:22: warning: array subscript 'union inputArgs[0]' is partly outside array bounds of 'unsigned char[20]' [-Warray-bounds] > 801 | sig_inputArgs->ih.opcode = CODA_SIGNAL; > | ^~ > In file included from ../include/linux/fs.h:45, > from ../include/linux/huge_mm.h:8, > from ../include/linux/mm.h:700, > from ../fs/coda/upcall.c:22: > In function 'kvmalloc', > inlined from 'kvzalloc' at ../include/linux/slab.h:758:9, > inlined from 'coda_upcall' at ../fs/coda/upcall.c:794:18: > ../include/linux/slab.h:750:16: note: object of size 20 allocated by 'kvmalloc_node' > 750 | return kvmalloc_node(size, flags, NUMA_NO_NODE); > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > ../fs/coda/upcall.c: In function 'coda_upcall': > ../fs/coda/upcall.c:802:22: warning: array subscript 'union inputArgs[0]' is partly outside array bounds of 'unsigned char[20]' [-Warray-bounds] > 802 | sig_inputArgs->ih.unique = req->uc_unique; > | ^~ > In function 'kvmalloc', > inlined from 'kvzalloc' at ../include/linux/slab.h:758:9, > inlined from 'coda_upcall' at ../fs/coda/upcall.c:794:18: > ../include/linux/slab.h:750:16: note: object of size 20 allocated by 'kvmalloc_node' > 750 | return kvmalloc_node(size, flags, NUMA_NO_NODE); > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > Cc: Jan Harkes > Cc: coda@cs.cmu.edu > Cc: codalist@coda.cs.cmu.edu > Signed-off-by: Kees Cook > --- > fs/coda/upcall.c | 20 ++++++++++---------- > 1 file changed, 10 insertions(+), 10 deletions(-) > > diff --git a/fs/coda/upcall.c b/fs/coda/upcall.c > index 59f6cfd06f96..21e4f5f446b2 100644 > --- a/fs/coda/upcall.c > +++ b/fs/coda/upcall.c > @@ -711,7 +711,7 @@ static int coda_upcall(struct venus_comm *vcp, > union inputArgs *buffer) > { > union outputArgs *out; > - union inputArgs *sig_inputArgs; > + struct coda_in_hdr *ih; > struct upc_req *req = NULL, *sig_req; > int error; > > @@ -791,22 +791,22 @@ static int coda_upcall(struct venus_comm *vcp, > sig_req = kmalloc(sizeof(struct upc_req), GFP_KERNEL); > if (!sig_req) goto exit; > > - sig_inputArgs = kvzalloc(sizeof(struct coda_in_hdr), GFP_KERNEL); > - if (!sig_inputArgs) { > + ih = kvzalloc(sizeof(*ih), GFP_KERNEL); > + if (!ih) { > kfree(sig_req); > goto exit; > } > > error = -EINTR; > - sig_inputArgs->ih.opcode = CODA_SIGNAL; > - sig_inputArgs->ih.unique = req->uc_unique; > + ih->opcode = CODA_SIGNAL; > + ih->unique = req->uc_unique; > > sig_req->uc_flags = CODA_REQ_ASYNC; > - sig_req->uc_opcode = sig_inputArgs->ih.opcode; > - sig_req->uc_unique = sig_inputArgs->ih.unique; > - sig_req->uc_data = (void *)sig_inputArgs; > - sig_req->uc_inSize = sizeof(struct coda_in_hdr); > - sig_req->uc_outSize = sizeof(struct coda_in_hdr); > + sig_req->uc_opcode = ih->opcode; > + sig_req->uc_unique = ih->unique; > + sig_req->uc_data = (void *)ih; > + sig_req->uc_inSize = sizeof(*ih); > + sig_req->uc_outSize = sizeof(*ih); > > /* insert at head of queue! */ > list_add(&(sig_req->uc_chain), &vcp->vc_pending); > -- > 2.32.0 > >