* [PATCH] nul-terminate readlink result @ 2015-07-11 9:02 Tobias Stoeckmann 2015-07-12 10:14 ` Tobias Stoeckmann 0 siblings, 1 reply; 3+ messages in thread From: Tobias Stoeckmann @ 2015-07-11 9:02 UTC (permalink / raw) To: dri-devel readlink by itself does not guarantee that its result is properly nul-terminated. Setting the last byte of the buffer to '\0' fixes this issue. --- libkms/linux.c | 1 + 1 file changed, 1 insertion(+) diff --git a/libkms/linux.c b/libkms/linux.c index 4d47148..667d37c 100644 --- a/libkms/linux.c +++ b/libkms/linux.c @@ -82,6 +82,7 @@ linux_name_from_sysfs(int fd, char **out) if (readlink(path, link, PATH_SIZE) < 0) return -EINVAL; + link[PATH_SIZE] = '\0'; /* link looks something like this: ../../../bus/pci/drivers/intel */ slash_name = strrchr(link, '/'); -- 2.4.5 _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/dri-devel ^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] nul-terminate readlink result 2015-07-11 9:02 [PATCH] nul-terminate readlink result Tobias Stoeckmann @ 2015-07-12 10:14 ` Tobias Stoeckmann 2015-07-13 15:42 ` Emil Velikov 0 siblings, 1 reply; 3+ messages in thread From: Tobias Stoeckmann @ 2015-07-12 10:14 UTC (permalink / raw) To: dri-devel On Sat, Jul 11, 2015 at 11:02:57AM +0200, Tobias Stoeckmann wrote: > if (readlink(path, link, PATH_SIZE) < 0) > return -EINVAL; > + link[PATH_SIZE] = '\0'; Sorry, this patch is wrong. It has to be terminated at the correct position. Please see this updated version: From a1840916dd370d5c84ebf23df91f1c13d564d212 Mon Sep 17 00:00:00 2001 From: Tobias Stoeckmann <tobias@stoeckmann.org> Date: Sun, 12 Jul 2015 12:10:59 +0200 Subject: [PATCH] nul-terminate readlink result readlink by itself does not terminate its result. The caller has to terminate the string at the proper position. --- libkms/linux.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/libkms/linux.c b/libkms/linux.c index 4d47148..5e2431f 100644 --- a/libkms/linux.c +++ b/libkms/linux.c @@ -55,6 +55,7 @@ linux_name_from_sysfs(int fd, char **out) unsigned maj, min; char* slash_name; int ret; + ssize_t len; /* * Inside the sysfs directory for the device there is a symlink @@ -80,8 +81,9 @@ linux_name_from_sysfs(int fd, char **out) snprintf(path, PATH_SIZE, "/sys/dev/char/%d:%d/device/driver", maj, min); - if (readlink(path, link, PATH_SIZE) < 0) + if ((len = readlink(path, link, PATH_SIZE)) < 0) return -EINVAL; + link[len] = '\0'; /* link looks something like this: ../../../bus/pci/drivers/intel */ slash_name = strrchr(link, '/'); -- 2.4.5 _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/dri-devel ^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] nul-terminate readlink result 2015-07-12 10:14 ` Tobias Stoeckmann @ 2015-07-13 15:42 ` Emil Velikov 0 siblings, 0 replies; 3+ messages in thread From: Emil Velikov @ 2015-07-13 15:42 UTC (permalink / raw) To: Tobias Stoeckmann; +Cc: ML dri-devel Hi Tobias, On 12 July 2015 at 11:14, Tobias Stoeckmann <tobias@stoeckmann.org> wrote: > On Sat, Jul 11, 2015 at 11:02:57AM +0200, Tobias Stoeckmann wrote: >> if (readlink(path, link, PATH_SIZE) < 0) >> return -EINVAL; >> + link[PATH_SIZE] = '\0'; > > Sorry, this patch is wrong. It has to be terminated at the correct > position. Please see this updated version: > Thanks for the update, there is a pick I'm afraid: > > From a1840916dd370d5c84ebf23df91f1c13d564d212 Mon Sep 17 00:00:00 2001 > From: Tobias Stoeckmann <tobias@stoeckmann.org> > Date: Sun, 12 Jul 2015 12:10:59 +0200 > Subject: [PATCH] nul-terminate readlink result > > readlink by itself does not terminate its result. The caller has > to terminate the string at the proper position. > --- > libkms/linux.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/libkms/linux.c b/libkms/linux.c > index 4d47148..5e2431f 100644 > --- a/libkms/linux.c > +++ b/libkms/linux.c > @@ -55,6 +55,7 @@ linux_name_from_sysfs(int fd, char **out) > unsigned maj, min; > char* slash_name; > int ret; > + ssize_t len; > > /* > * Inside the sysfs directory for the device there is a symlink > @@ -80,8 +81,9 @@ linux_name_from_sysfs(int fd, char **out) > > snprintf(path, PATH_SIZE, "/sys/dev/char/%d:%d/device/driver", maj, min); > > - if (readlink(path, link, PATH_SIZE) < 0) > + if ((len = readlink(path, link, PATH_SIZE)) < 0) > return -EINVAL; > + link[len] = '\0'; The man page does not say it -1 + errno is returned when the buffer is too small. There is ENAMETOOLONG which reads "A pathname, or a component of a pathname, was too long.". At the same time the example given explicitly checks for len >= PATH_SIZE. It uses lstat + malloc over a static storage. Not sure how much this matters here though. Thanks Emil _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/dri-devel ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2015-07-13 15:42 UTC | newest] Thread overview: 3+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2015-07-11 9:02 [PATCH] nul-terminate readlink result Tobias Stoeckmann 2015-07-12 10:14 ` Tobias Stoeckmann 2015-07-13 15:42 ` Emil Velikov
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