On Mon, Oct 10, 2022 at 11:52:43PM -0700, Kees Cook wrote: > The 'nfs_server' and 'mount_server' structures include a union of > 'struct sockaddr' (with the older 16 bytes max address size) and > 'struct sockaddr_storage' which is large enough to hold all the supported > sa_family types (128 bytes max size). The runtime memcpy() buffer overflow > checker is seeing attempts to write beyond the 16 bytes as an overflow, > but the actual expected size is that of 'struct sockaddr_storage'. Adjust > the pointers to the correct union member. Avoids this false positive > run-time warning under CONFIG_FORTIFY_SOURCE: > > memcpy: detected field-spanning write (size 28) of single field "&ctx->nfs_server.address" at fs/nfs/namespace.c:178 (size 16) > > Reported-by: kernel test robot <yujie.liu@xxxxxxxxx> > Link: https://lore.kernel.org/all/202210110948.26b43120-yujie.liu@xxxxxxxxx > Cc: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> > Cc: Anna Schumaker <anna@xxxxxxxxxx> > Cc: linux-nfs@xxxxxxxxxxxxxxx > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> Reviewed-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx> Thanks! -- Gustavo > --- > fs/nfs/fs_context.c | 2 +- > fs/nfs/namespace.c | 2 +- > fs/nfs/super.c | 4 ++-- > 3 files changed, 4 insertions(+), 4 deletions(-) > > diff --git a/fs/nfs/fs_context.c b/fs/nfs/fs_context.c > index 4da701fd1424..bffa31bb35b9 100644 > --- a/fs/nfs/fs_context.c > +++ b/fs/nfs/fs_context.c > @@ -1540,7 +1540,7 @@ static int nfs_init_fs_context(struct fs_context *fc) > ctx->version = nfss->nfs_client->rpc_ops->version; > ctx->minorversion = nfss->nfs_client->cl_minorversion; > > - memcpy(&ctx->nfs_server.address, &nfss->nfs_client->cl_addr, > + memcpy(&ctx->nfs_server._address, &nfss->nfs_client->cl_addr, > ctx->nfs_server.addrlen); > > if (fc->net_ns != net) { > diff --git a/fs/nfs/namespace.c b/fs/nfs/namespace.c > index 3295af4110f1..2f336ace7555 100644 > --- a/fs/nfs/namespace.c > +++ b/fs/nfs/namespace.c > @@ -175,7 +175,7 @@ struct vfsmount *nfs_d_automount(struct path *path) > } > > /* for submounts we want the same server; referrals will reassign */ > - memcpy(&ctx->nfs_server.address, &client->cl_addr, client->cl_addrlen); > + memcpy(&ctx->nfs_server._address, &client->cl_addr, client->cl_addrlen); > ctx->nfs_server.addrlen = client->cl_addrlen; > ctx->nfs_server.port = server->port; > > diff --git a/fs/nfs/super.c b/fs/nfs/super.c > index 82944e14fcea..8ea7dfdea427 100644 > --- a/fs/nfs/super.c > +++ b/fs/nfs/super.c > @@ -823,7 +823,7 @@ static int nfs_request_mount(struct fs_context *fc, > struct nfs_fs_context *ctx = nfs_fc2context(fc); > struct nfs_mount_request request = { > .sap = (struct sockaddr *) > - &ctx->mount_server.address, > + &ctx->mount_server._address, > .dirpath = ctx->nfs_server.export_path, > .protocol = ctx->mount_server.protocol, > .fh = root_fh, > @@ -854,7 +854,7 @@ static int nfs_request_mount(struct fs_context *fc, > * Construct the mount server's address. > */ > if (ctx->mount_server.address.sa_family == AF_UNSPEC) { > - memcpy(request.sap, &ctx->nfs_server.address, > + memcpy(request.sap, &ctx->nfs_server._address, > ctx->nfs_server.addrlen); > ctx->mount_server.addrlen = ctx->nfs_server.addrlen; > } > -- > 2.34.1 >
