The snprintf() function returns the number of bytes which would have
been printed if the buffer was large enough. In other words it can
return ">= remain" but this code assumes it returns "== remain".
The run time impact of this bug is not very severe. The next iteration
through the loop would trigger a WARN() when we pass a negative limit
to snprintf(). We would then return success instead of -E2BIG.
The kernel implementation of snprintf() will never return negatives so
there is no need to check and I have deleted that dead code.
Fixes: a860f6eb4c6a ("ocfs2: sysfile interfaces for online file check")
Signed-off-by: Dan Carpenter <[email protected]>
---
fs/ocfs2/filecheck.c | 6 +-----
fs/ocfs2/stackglue.c | 8 ++------
2 files changed, 3 insertions(+), 11 deletions(-)
diff --git a/fs/ocfs2/filecheck.c b/fs/ocfs2/filecheck.c
index 90b8d300c1ee..de56e6231af8 100644
--- a/fs/ocfs2/filecheck.c
+++ b/fs/ocfs2/filecheck.c
@@ -326,11 +326,7 @@ static ssize_t ocfs2_filecheck_attr_show(struct kobject *kobj,
ret = snprintf(buf + total, remain, "%lu\t\t%u\t%s\n",
p->fe_ino, p->fe_done,
ocfs2_filecheck_error(p->fe_status));
- if (ret < 0) {
- total = ret;
- break;
- }
- if (ret == remain) {
+ if (ret >= remain) {
/* snprintf() didn't fit */
total = -E2BIG;
break;
diff --git a/fs/ocfs2/stackglue.c b/fs/ocfs2/stackglue.c
index d50e8b8dfea4..16f1bfc407f2 100644
--- a/fs/ocfs2/stackglue.c
+++ b/fs/ocfs2/stackglue.c
@@ -500,11 +500,7 @@ static ssize_t ocfs2_loaded_cluster_plugins_show(struct kobject *kobj,
list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
ret = snprintf(buf, remain, "%s\n",
p->sp_name);
- if (ret < 0) {
- total = ret;
- break;
- }
- if (ret == remain) {
+ if (ret >= remain) {
/* snprintf() didn't fit */
total = -E2BIG;
break;
@@ -531,7 +527,7 @@ static ssize_t ocfs2_active_cluster_plugin_show(struct kobject *kobj,
if (active_stack) {
ret = snprintf(buf, PAGE_SIZE, "%s\n",
active_stack->sp_name);
- if (ret == PAGE_SIZE)
+ if (ret >= PAGE_SIZE)
ret = -E2BIG;
}
spin_unlock(&ocfs2_stack_lock);
--
2.30.2
On 5/11/21 3:16 PM, Dan Carpenter wrote:
> The snprintf() function returns the number of bytes which would have
> been printed if the buffer was large enough. In other words it can
> return ">= remain" but this code assumes it returns "== remain".
>
> The run time impact of this bug is not very severe. The next iteration
> through the loop would trigger a WARN() when we pass a negative limit
> to snprintf(). We would then return success instead of -E2BIG.
>
> The kernel implementation of snprintf() will never return negatives so
> there is no need to check and I have deleted that dead code.
>
> Fixes: a860f6eb4c6a ("ocfs2: sysfile interfaces for online file check")
> Signed-off-by: Dan Carpenter <[email protected]>
Looks good. But the last 2 sections are introduced by:
74ae4e104dfc ocfs2: Create stack glue sysfs files.
With 'Fixes' tag updated,
Reviewed-by: Joseph Qi <[email protected]>
> ---
> fs/ocfs2/filecheck.c | 6 +-----
> fs/ocfs2/stackglue.c | 8 ++------
> 2 files changed, 3 insertions(+), 11 deletions(-)
>
> diff --git a/fs/ocfs2/filecheck.c b/fs/ocfs2/filecheck.c
> index 90b8d300c1ee..de56e6231af8 100644
> --- a/fs/ocfs2/filecheck.c
> +++ b/fs/ocfs2/filecheck.c
> @@ -326,11 +326,7 @@ static ssize_t ocfs2_filecheck_attr_show(struct kobject *kobj,
> ret = snprintf(buf + total, remain, "%lu\t\t%u\t%s\n",
> p->fe_ino, p->fe_done,
> ocfs2_filecheck_error(p->fe_status));
> - if (ret < 0) {
> - total = ret;
> - break;
> - }
> - if (ret == remain) {
> + if (ret >= remain) {
> /* snprintf() didn't fit */
> total = -E2BIG;
> break;
> diff --git a/fs/ocfs2/stackglue.c b/fs/ocfs2/stackglue.c
> index d50e8b8dfea4..16f1bfc407f2 100644
> --- a/fs/ocfs2/stackglue.c
> +++ b/fs/ocfs2/stackglue.c
> @@ -500,11 +500,7 @@ static ssize_t ocfs2_loaded_cluster_plugins_show(struct kobject *kobj,
> list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
> ret = snprintf(buf, remain, "%s\n",
> p->sp_name);
> - if (ret < 0) {
> - total = ret;
> - break;
> - }
> - if (ret == remain) {
> + if (ret >= remain) {
> /* snprintf() didn't fit */
> total = -E2BIG;
> break;
> @@ -531,7 +527,7 @@ static ssize_t ocfs2_active_cluster_plugin_show(struct kobject *kobj,
> if (active_stack) {
> ret = snprintf(buf, PAGE_SIZE, "%s\n",
> active_stack->sp_name);
> - if (ret == PAGE_SIZE)
> + if (ret >= PAGE_SIZE)
> ret = -E2BIG;
> }
> spin_unlock(&ocfs2_stack_lock);
>
On Tue, May 11, 2021 at 08:54:53PM +0800, Joseph Qi wrote:
>
>
> On 5/11/21 3:16 PM, Dan Carpenter wrote:
> > The snprintf() function returns the number of bytes which would have
> > been printed if the buffer was large enough. In other words it can
> > return ">= remain" but this code assumes it returns "== remain".
> >
> > The run time impact of this bug is not very severe. The next iteration
> > through the loop would trigger a WARN() when we pass a negative limit
> > to snprintf(). We would then return success instead of -E2BIG.
> >
> > The kernel implementation of snprintf() will never return negatives so
> > there is no need to check and I have deleted that dead code.
> >
> > Fixes: a860f6eb4c6a ("ocfs2: sysfile interfaces for online file check")
> > Signed-off-by: Dan Carpenter <[email protected]>
>
> Looks good. But the last 2 sections are introduced by:
> 74ae4e104dfc ocfs2: Create stack glue sysfs files.
>
> With 'Fixes' tag updated,
> Reviewed-by: Joseph Qi <[email protected]>
>
Thanks! Will do.
regards,
dan carpenter
The snprintf() function returns the number of bytes which would have
been printed if the buffer was large enough. In other words it can
return ">= remain" but this code assumes it returns "== remain".
The run time impact of this bug is not very severe. The next iteration
through the loop would trigger a WARN() when we pass a negative limit
to snprintf(). We would then return success instead of -E2BIG.
The kernel implementation of snprintf() will never return negatives so
there is no need to check and I have deleted that dead code.
Fixes: a860f6eb4c6a ("ocfs2: sysfile interfaces for online file check")
Fixes: 74ae4e104dfc ("ocfs2: Create stack glue sysfs files.")
Signed-off-by: Dan Carpenter <[email protected]>
Reviewed-by: Joseph Qi <[email protected]>
---
v2: update the Fixes tag, add Joseph's R-b tag.
fs/ocfs2/filecheck.c | 6 +-----
fs/ocfs2/stackglue.c | 8 ++------
2 files changed, 3 insertions(+), 11 deletions(-)
diff --git a/fs/ocfs2/filecheck.c b/fs/ocfs2/filecheck.c
index 90b8d300c1ee..de56e6231af8 100644
--- a/fs/ocfs2/filecheck.c
+++ b/fs/ocfs2/filecheck.c
@@ -326,11 +326,7 @@ static ssize_t ocfs2_filecheck_attr_show(struct kobject *kobj,
ret = snprintf(buf + total, remain, "%lu\t\t%u\t%s\n",
p->fe_ino, p->fe_done,
ocfs2_filecheck_error(p->fe_status));
- if (ret < 0) {
- total = ret;
- break;
- }
- if (ret == remain) {
+ if (ret >= remain) {
/* snprintf() didn't fit */
total = -E2BIG;
break;
diff --git a/fs/ocfs2/stackglue.c b/fs/ocfs2/stackglue.c
index d50e8b8dfea4..16f1bfc407f2 100644
--- a/fs/ocfs2/stackglue.c
+++ b/fs/ocfs2/stackglue.c
@@ -500,11 +500,7 @@ static ssize_t ocfs2_loaded_cluster_plugins_show(struct kobject *kobj,
list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
ret = snprintf(buf, remain, "%s\n",
p->sp_name);
- if (ret < 0) {
- total = ret;
- break;
- }
- if (ret == remain) {
+ if (ret >= remain) {
/* snprintf() didn't fit */
total = -E2BIG;
break;
@@ -531,7 +527,7 @@ static ssize_t ocfs2_active_cluster_plugin_show(struct kobject *kobj,
if (active_stack) {
ret = snprintf(buf, PAGE_SIZE, "%s\n",
active_stack->sp_name);
- if (ret == PAGE_SIZE)
+ if (ret >= PAGE_SIZE)
ret = -E2BIG;
}
spin_unlock(&ocfs2_stack_lock);
--
2.30.2