* [PATCH] procfs: Fix error handling of proc_register()
@ 2014-10-16 20:46 Debabrata Banerjee
2014-10-22 22:40 ` Andrew Morton
0 siblings, 1 reply; 3+ messages in thread
From: Debabrata Banerjee @ 2014-10-16 20:46 UTC (permalink / raw)
To: kdevcore; +Cc: Debabrata Banerjee, linux-fsdevel
I don't see why this should print warnings at all instead of properly
unrolling allocations and returning an appropriate error. It's actually
leaking resources currently.
to: Alexander Viro <viro@zeniv.linux.org.uk>
to: linux-kernel@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Debabrata Banerjee <dbanerje@akamai.com>
---
fs/proc/generic.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index 317b726..89b20cc 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -304,6 +304,7 @@ static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp
dp->proc_iops = &proc_file_inode_operations;
} else {
WARN_ON(1);
+ proc_free_inum(dp->low_ino);
return -EINVAL;
}
@@ -311,9 +312,13 @@ static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp
for (tmp = dir->subdir; tmp; tmp = tmp->next)
if (strcmp(tmp->name, dp->name) == 0) {
- WARN(1, "proc_dir_entry '%s/%s' already registered\n",
- dir->name, dp->name);
- break;
+ spin_unlock(&proc_subdir_lock);
+
+ if (S_ISDIR(dp->mode))
+ dir->nlink--;
+
+ proc_free_inum(dp->low_ino);
+ return -EEXIST;
}
dp->next = dir->subdir;
--
2.1.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] procfs: Fix error handling of proc_register()
2014-10-16 20:46 [PATCH] procfs: Fix error handling of proc_register() Debabrata Banerjee
@ 2014-10-22 22:40 ` Andrew Morton
2014-10-23 7:23 ` Nicolas Dichtel
0 siblings, 1 reply; 3+ messages in thread
From: Andrew Morton @ 2014-10-22 22:40 UTC (permalink / raw)
To: Debabrata Banerjee; +Cc: kdevcore, linux-fsdevel, Nicolas Dichtel
On Thu, 16 Oct 2014 16:46:02 -0400 Debabrata Banerjee <dbanerje@akamai.com> wrote:
> I don't see why this should print warnings at all instead of properly
> unrolling allocations and returning an appropriate error. It's actually
> leaking resources currently.
I think the warnings are useful - a duplicate name in /proc is a
significant kernel bug and we'll want to know precisely what caused it
and get it fixed up quickly. So let's keep that bit.
> --- a/fs/proc/generic.c
> +++ b/fs/proc/generic.c
> @@ -304,6 +304,7 @@ static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp
> dp->proc_iops = &proc_file_inode_operations;
> } else {
> WARN_ON(1);
> + proc_free_inum(dp->low_ino);
> return -EINVAL;
> }
>
> @@ -311,9 +312,13 @@ static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp
>
> for (tmp = dir->subdir; tmp; tmp = tmp->next)
> if (strcmp(tmp->name, dp->name) == 0) {
> - WARN(1, "proc_dir_entry '%s/%s' already registered\n",
> - dir->name, dp->name);
> - break;
> + spin_unlock(&proc_subdir_lock);
> +
> + if (S_ISDIR(dp->mode))
> + dir->nlink--;
> +
> + proc_free_inum(dp->low_ino);
> + return -EEXIST;
> }
Your patch conflicts somewhat with Nicolas's "fs/proc: use a rb tree for
the directory entries". Here's what I ended up with:
From: Debabrata Banerjee <dbanerje@akamai.com>
Subject: procfs: fix error handling of proc_register()
proc_register() error paths are leaking inodes and directory refcounts.
Signed-off-by: Debabrata Banerjee <dbanerje@akamai.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
fs/proc/generic.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff -puN fs/proc/generic.c~procfs-fix-error-handling-of-proc_register fs/proc/generic.c
--- a/fs/proc/generic.c~procfs-fix-error-handling-of-proc_register
+++ a/fs/proc/generic.c
@@ -369,14 +369,21 @@ static int proc_register(struct proc_dir
dp->proc_iops = &proc_file_inode_operations;
} else {
WARN_ON(1);
+ proc_free_inum(dp->low_ino);
return -EINVAL;
}
spin_lock(&proc_subdir_lock);
dp->parent = dir;
- if (pde_subdir_insert(dir, dp) == false)
+ if (pde_subdir_insert(dir, dp) == false) {
WARN(1, "proc_dir_entry '%s/%s' already registered\n",
dir->name, dp->name);
+ spin_unlock(&proc_subdir_lock);
+ if (S_ISDIR(dp->mode))
+ dir->nlink--;
+ proc_free_inum(dp->low_ino);
+ return -EEXIST;
+ }
spin_unlock(&proc_subdir_lock);
return 0;
_
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] procfs: Fix error handling of proc_register()
2014-10-22 22:40 ` Andrew Morton
@ 2014-10-23 7:23 ` Nicolas Dichtel
0 siblings, 0 replies; 3+ messages in thread
From: Nicolas Dichtel @ 2014-10-23 7:23 UTC (permalink / raw)
To: Andrew Morton, Debabrata Banerjee; +Cc: kdevcore, linux-fsdevel
Le 23/10/2014 00:40, Andrew Morton a écrit :
> On Thu, 16 Oct 2014 16:46:02 -0400 Debabrata Banerjee <dbanerje@akamai.com> wrote:
>
>> I don't see why this should print warnings at all instead of properly
>> unrolling allocations and returning an appropriate error. It's actually
>> leaking resources currently.
>
> I think the warnings are useful - a duplicate name in /proc is a
> significant kernel bug and we'll want to know precisely what caused it
> and get it fixed up quickly. So let's keep that bit.
>
>> --- a/fs/proc/generic.c
>> +++ b/fs/proc/generic.c
>> @@ -304,6 +304,7 @@ static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp
>> dp->proc_iops = &proc_file_inode_operations;
>> } else {
>> WARN_ON(1);
>> + proc_free_inum(dp->low_ino);
>> return -EINVAL;
>> }
>>
>> @@ -311,9 +312,13 @@ static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp
>>
>> for (tmp = dir->subdir; tmp; tmp = tmp->next)
>> if (strcmp(tmp->name, dp->name) == 0) {
>> - WARN(1, "proc_dir_entry '%s/%s' already registered\n",
>> - dir->name, dp->name);
>> - break;
>> + spin_unlock(&proc_subdir_lock);
>> +
>> + if (S_ISDIR(dp->mode))
>> + dir->nlink--;
>> +
>> + proc_free_inum(dp->low_ino);
>> + return -EEXIST;
>> }
>
> Your patch conflicts somewhat with Nicolas's "fs/proc: use a rb tree for
> the directory entries". Here's what I ended up with:
>
>
>
> From: Debabrata Banerjee <dbanerje@akamai.com>
> Subject: procfs: fix error handling of proc_register()
>
> proc_register() error paths are leaking inodes and directory refcounts.
>
> Signed-off-by: Debabrata Banerjee <dbanerje@akamai.com>
> Cc: Alexander Viro <viro@zeniv.linux.org.uk>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
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2014-10-16 20:46 [PATCH] procfs: Fix error handling of proc_register() Debabrata Banerjee
2014-10-22 22:40 ` Andrew Morton
2014-10-23 7:23 ` Nicolas Dichtel
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