Yeah, but this same pattern is used elsewhere in the file, so I went with
being consistent.
On Thu, Jan 6, 2022, 2:44 PM Philippe Mathieu-Daudé <f4...@amsat.org> wrote:
> On 6/1/22 19:28, Patrick Venture wrote:
> > From: Peter Foley <pefo...@google.com>
> >
> > e.g.
> > 1109 15:16:20.151506 Uninitialized bytes in ioctl_common_pre at offset 0
> inside [0x7ffc516af9b8, 4)
> > 1109 15:16:20.151659 ==588974==WARNING: MemorySanitizer:
> use-of-uninitialized-value
> > 1109 15:16:20.312923 #0 0x5639b88acb21 in tap_probe_vnet_hdr_len
> third_party/qemu/net/tap-linux.c:183:9
> > 1109 15:16:20.312952 #1 0x5639b88afd66 in net_tap_fd_init
> third_party/qemu/net/tap.c:409:9
> > 1109 15:16:20.312954 #2 0x5639b88b2d1b in net_init_tap_one
> third_party/qemu/net/tap.c:681:19
> > 1109 15:16:20.312956 #3 0x5639b88b16a8 in net_init_tap
> third_party/qemu/net/tap.c:912:13
> > 1109 15:16:20.312957 #4 0x5639b8890175 in net_client_init1
> third_party/qemu/net/net.c:1110:9
> > 1109 15:16:20.312958 #5 0x5639b888f912 in net_client_init
> third_party/qemu/net/net.c:1208:15
> > 1109 15:16:20.312960 #6 0x5639b8894aa5 in net_param_nic
> third_party/qemu/net/net.c:1588:11
> > 1109 15:16:20.312961 #7 0x5639b900cd18 in qemu_opts_foreach
> third_party/qemu/util/qemu-option.c:1135:14
> > 1109 15:16:20.312962 #8 0x5639b889393c in net_init_clients
> third_party/qemu/net/net.c:1612:9
> > 1109 15:16:20.312964 #9 0x5639b717aaf3 in
> qemu_create_late_backends third_party/qemu/softmmu/vl.c:1962:5
> > 1109 15:16:20.312965 #10 0x5639b717aaf3 in qemu_init
> third_party/qemu/softmmu/vl.c:3694:5
> > 1109 15:16:20.312967 #11 0x5639b71083b8 in main
> third_party/qemu/softmmu/main.c:49:5
> > 1109 15:16:20.312968 #12 0x7f464de1d8d2 in __libc_start_main
> (/usr/grte/v5/lib64/libc.so.6+0x628d2)
> > 1109 15:16:20.312969 #13 0x5639b6bbd389 in _start
> /usr/grte/v5/debug-src/src/csu/../sysdeps/x86_64/start.S:120
> > 1109 15:16:20.312970
> > 1109 15:16:20.312975 Uninitialized value was stored to memory at
> > 1109 15:16:20.313393 #0 0x5639b88acbee in tap_probe_vnet_hdr_len
> third_party/qemu/net/tap-linux.c
> > 1109 15:16:20.313396 #1 0x5639b88afd66 in net_tap_fd_init
> third_party/qemu/net/tap.c:409:9
> > 1109 15:16:20.313398 #2 0x5639b88b2d1b in net_init_tap_one
> third_party/qemu/net/tap.c:681:19
> > 1109 15:16:20.313399 #3 0x5639b88b16a8 in net_init_tap
> third_party/qemu/net/tap.c:912:13
> > 1109 15:16:20.313400 #4 0x5639b8890175 in net_client_init1
> third_party/qemu/net/net.c:1110:9
> > 1109 15:16:20.313401 #5 0x5639b888f912 in net_client_init
> third_party/qemu/net/net.c:1208:15
> > 1109 15:16:20.313403 #6 0x5639b8894aa5 in net_param_nic
> third_party/qemu/net/net.c:1588:11
> > 1109 15:16:20.313404 #7 0x5639b900cd18 in qemu_opts_foreach
> third_party/qemu/util/qemu-option.c:1135:14
> > 1109 15:16:20.313405 #8 0x5639b889393c in net_init_clients
> third_party/qemu/net/net.c:1612:9
> > 1109 15:16:20.313407 #9 0x5639b717aaf3 in
> qemu_create_late_backends third_party/qemu/softmmu/vl.c:1962:5
> > 1109 15:16:20.313408 #10 0x5639b717aaf3 in qemu_init
> third_party/qemu/softmmu/vl.c:3694:5
> > 1109 15:16:20.313409 #11 0x5639b71083b8 in main
> third_party/qemu/softmmu/main.c:49:5
> > 1109 15:16:20.313410 #12 0x7f464de1d8d2 in __libc_start_main
> (/usr/grte/v5/lib64/libc.so.6+0x628d2)
> > 1109 15:16:20.313412 #13 0x5639b6bbd389 in _start
> /usr/grte/v5/debug-src/src/csu/../sysdeps/x86_64/start.S:120
> > 1109 15:16:20.313413
> > 1109 15:16:20.313417 Uninitialized value was stored to memory at
> > 1109 15:16:20.313791 #0 0x5639b88affbd in net_tap_fd_init
> third_party/qemu/net/tap.c:400:26
> > 1109 15:16:20.313826 #1 0x5639b88b2d1b in net_init_tap_one
> third_party/qemu/net/tap.c:681:19
> > 1109 15:16:20.313829 #2 0x5639b88b16a8 in net_init_tap
> third_party/qemu/net/tap.c:912:13
> > 1109 15:16:20.313831 #3 0x5639b8890175 in net_client_init1
> third_party/qemu/net/net.c:1110:9
> > 1109 15:16:20.313836 #4 0x5639b888f912 in net_client_init
> third_party/qemu/net/net.c:1208:15
> > 1109 15:16:20.313838 #5 0x5639b8894aa5 in net_param_nic
> third_party/qemu/net/net.c:1588:11
> > 1109 15:16:20.313839 #6 0x5639b900cd18 in qemu_opts_foreach
> third_party/qemu/util/qemu-option.c:1135:14
> > 1109 15:16:20.313841 #7 0x5639b889393c in net_init_clients
> third_party/qemu/net/net.c:1612:9
> > 1109 15:16:20.313843 #8 0x5639b717aaf3 in
> qemu_create_late_backends third_party/qemu/softmmu/vl.c:1962:5
> > 1109 15:16:20.313844 #9 0x5639b717aaf3 in qemu_init
> third_party/qemu/softmmu/vl.c:3694:5
> > 1109 15:16:20.313845 #10 0x5639b71083b8 in main
> third_party/qemu/softmmu/main.c:49:5
> > 1109 15:16:20.313846 #11 0x7f464de1d8d2 in __libc_start_main
> (/usr/grte/v5/lib64/libc.so.6+0x628d2)
> > 1109 15:16:20.313847 #12 0x5639b6bbd389 in _start
> /usr/grte/v5/debug-src/src/csu/../sysdeps/x86_64/start.S:120
> > 1109 15:16:20.313849
> > 1109 15:16:20.313851 Uninitialized value was created by an
> allocation of 'ifr' in the stack frame of function 'tap_probe_vnet_hdr'
> > 1109 15:16:20.313855 #0 0x5639b88ac680 in tap_probe_vnet_hdr
> third_party/qemu/net/tap-linux.c:151
> > 1109 15:16:20.313856
> > 1109 15:16:20.313878 SUMMARY: MemorySanitizer:
> use-of-uninitialized-value third_party/qemu/net/tap-linux.c:183:9 in
> tap_probe_vnet_hdr_len
> >
> > Fixes: dc69004c7d8 ("net: move tap_probe_vnet_hdr() to tap-linux.c")
> > Reviewed-by: Hao Wu <wuhao...@google.com>
> > Reviewed-by: Patrick Venture <vent...@google.com>
> > Signed-off-by: Peter Foley <pefo...@google.com>
> > ---
> > net/tap-linux.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/net/tap-linux.c b/net/tap-linux.c
> > index 9584769740..5e70b93037 100644
> > --- a/net/tap-linux.c
> > +++ b/net/tap-linux.c
> > @@ -150,6 +150,7 @@ void tap_set_sndbuf(int fd, const NetdevTapOptions
> *tap, Error **errp)
> > int tap_probe_vnet_hdr(int fd, Error **errp)
> > {
> > struct ifreq ifr;
> > + memset(&ifr, 0, sizeof(ifr));
>
> Or:
>
> struct ifreq ifr = { };
>
> Reviewed-by: Philippe Mathieu-Daudé <f4...@amsat.org>
>
> >
> > if (ioctl(fd, TUNGETIFF, &ifr) != 0) {
> > /* TUNGETIFF is available since kernel v2.6.27 */
>
>
