| Message ID | 1478005669-3752-2-git-send-email-ernunes@redhat.com |
|---|---|
| State | Accepted |
| Headers | show |
On 01/11/16 07:07, Erico Nunes wrote: > When building the current fwts release with an older gcc 4.4, we get the > following error due to breaking strict-aliasing rules, despite the > comment in the code which states there has been an attempt to solve this > in the past: > > fwts_hwinfo.c: In function ‘fwts_hwinfo_get’: > fwts_hwinfo.c:420: error: dereferencing pointer ‘sockaddr’ does break > strict-aliasing rules > fwts_hwinfo.c:419: note: initialized from here > > This new attempt to fix it just makes a copy of the whole "buf.ifr_addr" > to into sockaddr to avoid running into any strict-aliasing problems. > As there are still supported systems with older gcc versions, such as > RHEL6, it is interesting to have this fixed. > > This has been built and tested with gcc 6.2.1, gcc 4.8.5 and gcc 4.4.7. > > Signed-off-by: Erico Nunes <ernunes@redhat.com> > --- > src/lib/src/fwts_hwinfo.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/src/lib/src/fwts_hwinfo.c b/src/lib/src/fwts_hwinfo.c > index 083b94d..d749cf2 100644 > --- a/src/lib/src/fwts_hwinfo.c > +++ b/src/lib/src/fwts_hwinfo.c > @@ -381,7 +381,7 @@ static int fwts_hwinfo_net_get( > > while ((d = readdir(dp)) != NULL) { > struct ifreq buf; > - struct sockaddr_in *sockaddr; > + struct sockaddr_in sockaddr; > fwts_net_config *net_config; > > if (d->d_name[0] == '.') > @@ -416,8 +416,8 @@ static int fwts_hwinfo_net_get( > fwts_log_error(fw, "Cannot get address for device %s.", d->d_name); > } > /* GCC 4.4 is rather overly pedantic in strict aliasing warnings, this avoids it */ > - sockaddr = (struct sockaddr_in *)&buf.ifr_addr; > - net_config->addr = strdup(inet_ntoa((struct in_addr)sockaddr->sin_addr)); > + memcpy(&sockaddr, &buf.ifr_addr, sizeof(sockaddr)); > + net_config->addr = strdup(inet_ntoa((struct in_addr)sockaddr.sin_addr)); > if (net_config->addr == NULL) { > fwts_log_error(fw, "Cannot allocate net config H/W address."); > fwts_hwinfo_net_free(net_config); > Thanks for sorting this one out. Acked-by: Colin Ian King <colin.king@canonical.com>
On 2016-11-01 06:07 AM, Erico Nunes wrote: > When building the current fwts release with an older gcc 4.4, we get the > following error due to breaking strict-aliasing rules, despite the > comment in the code which states there has been an attempt to solve this > in the past: > > fwts_hwinfo.c: In function ‘fwts_hwinfo_get’: > fwts_hwinfo.c:420: error: dereferencing pointer ‘sockaddr’ does break > strict-aliasing rules > fwts_hwinfo.c:419: note: initialized from here > > This new attempt to fix it just makes a copy of the whole "buf.ifr_addr" > to into sockaddr to avoid running into any strict-aliasing problems. > As there are still supported systems with older gcc versions, such as > RHEL6, it is interesting to have this fixed. > > This has been built and tested with gcc 6.2.1, gcc 4.8.5 and gcc 4.4.7. > > Signed-off-by: Erico Nunes <ernunes@redhat.com> > --- > src/lib/src/fwts_hwinfo.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/src/lib/src/fwts_hwinfo.c b/src/lib/src/fwts_hwinfo.c > index 083b94d..d749cf2 100644 > --- a/src/lib/src/fwts_hwinfo.c > +++ b/src/lib/src/fwts_hwinfo.c > @@ -381,7 +381,7 @@ static int fwts_hwinfo_net_get( > > while ((d = readdir(dp)) != NULL) { > struct ifreq buf; > - struct sockaddr_in *sockaddr; > + struct sockaddr_in sockaddr; > fwts_net_config *net_config; > > if (d->d_name[0] == '.') > @@ -416,8 +416,8 @@ static int fwts_hwinfo_net_get( > fwts_log_error(fw, "Cannot get address for device %s.", d->d_name); > } > /* GCC 4.4 is rather overly pedantic in strict aliasing warnings, this avoids it */ > - sockaddr = (struct sockaddr_in *)&buf.ifr_addr; > - net_config->addr = strdup(inet_ntoa((struct in_addr)sockaddr->sin_addr)); > + memcpy(&sockaddr, &buf.ifr_addr, sizeof(sockaddr)); > + net_config->addr = strdup(inet_ntoa((struct in_addr)sockaddr.sin_addr)); > if (net_config->addr == NULL) { > fwts_log_error(fw, "Cannot allocate net config H/W address."); > fwts_hwinfo_net_free(net_config); > Acked-by: Alex Hung <alex.hung@canonical.com>
diff --git a/src/lib/src/fwts_hwinfo.c b/src/lib/src/fwts_hwinfo.c index 083b94d..d749cf2 100644 --- a/src/lib/src/fwts_hwinfo.c +++ b/src/lib/src/fwts_hwinfo.c @@ -381,7 +381,7 @@ static int fwts_hwinfo_net_get( while ((d = readdir(dp)) != NULL) { struct ifreq buf; - struct sockaddr_in *sockaddr; + struct sockaddr_in sockaddr; fwts_net_config *net_config; if (d->d_name[0] == '.') @@ -416,8 +416,8 @@ static int fwts_hwinfo_net_get( fwts_log_error(fw, "Cannot get address for device %s.", d->d_name); } /* GCC 4.4 is rather overly pedantic in strict aliasing warnings, this avoids it */ - sockaddr = (struct sockaddr_in *)&buf.ifr_addr; - net_config->addr = strdup(inet_ntoa((struct in_addr)sockaddr->sin_addr)); + memcpy(&sockaddr, &buf.ifr_addr, sizeof(sockaddr)); + net_config->addr = strdup(inet_ntoa((struct in_addr)sockaddr.sin_addr)); if (net_config->addr == NULL) { fwts_log_error(fw, "Cannot allocate net config H/W address."); fwts_hwinfo_net_free(net_config);
When building the current fwts release with an older gcc 4.4, we get the following error due to breaking strict-aliasing rules, despite the comment in the code which states there has been an attempt to solve this in the past: fwts_hwinfo.c: In function ‘fwts_hwinfo_get’: fwts_hwinfo.c:420: error: dereferencing pointer ‘sockaddr’ does break strict-aliasing rules fwts_hwinfo.c:419: note: initialized from here This new attempt to fix it just makes a copy of the whole "buf.ifr_addr" to into sockaddr to avoid running into any strict-aliasing problems. As there are still supported systems with older gcc versions, such as RHEL6, it is interesting to have this fixed. This has been built and tested with gcc 6.2.1, gcc 4.8.5 and gcc 4.4.7. Signed-off-by: Erico Nunes <ernunes@redhat.com> --- src/lib/src/fwts_hwinfo.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)