On 10/25/2017 02:50 AM, Juerg Haefliger wrote:
> Is this a patch you might consider?
Sorry it's taken me so long to respond.
I don't think this is the right fix. A failed allocation will still
result in a null pointer dereference by the caller, __get_metapage(). I
think the check needs to be put there. Like this:
--- a/fs/jfs/jfs_metapage.c
+++ b/fs/jfs/jfs_metapage.c
@@ -663,6 +663,8 @@ struct metapage *__get_metapage(struct inode *inode,
unsigned long lblock,
} else {
INCREMENT(mpStat.pagealloc);
mp = alloc_metapage(GFP_NOFS);
+ if (!mp)
+ goto unlock;
mp->page = page;
mp->sb = inode->i_sb;
mp->flag = 0;
Furthermore, it looks like all the callers of __get_metapage() check for
a null return, so I'm not sure we need to handle the error at this
point. I might have to look a bit harder at that, since there are many
callers.
Thanks,
Shaggy
>
> Thanks
> ...Juerg
>
>
> On 10/04/2017 10:24 AM, Juerg Haefliger wrote:
>> alloc_metapage can return a NULL pointer so check for that. And also emit
>> an error message if that happens.
>>
>> Signed-off-by: Juerg Haefliger <[email protected]>
>> ---
>> fs/jfs/jfs_metapage.c | 20 +++++++++++++-------
>> 1 file changed, 13 insertions(+), 7 deletions(-)
>>
>> diff --git a/fs/jfs/jfs_metapage.c b/fs/jfs/jfs_metapage.c
>> index 1c4b9ad4d7ab..00f21af66872 100644
>> --- a/fs/jfs/jfs_metapage.c
>> +++ b/fs/jfs/jfs_metapage.c
>> @@ -187,14 +187,18 @@ static inline struct metapage *alloc_metapage(gfp_t gfp_mask)
>> {
>> struct metapage *mp = mempool_alloc(metapage_mempool, gfp_mask);
>>
>> - if (mp) {
>> - mp->lid = 0;
>> - mp->lsn = 0;
>> - mp->data = NULL;
>> - mp->clsn = 0;
>> - mp->log = NULL;
>> - init_waitqueue_head(&mp->wait);
>> + if (!mp) {
>> + jfs_err("mempool_alloc failed!\n");
>> + return NULL;
>> }
>> +
>> + mp->lid = 0;
>> + mp->lsn = 0;
>> + mp->data = NULL;
>> + mp->clsn = 0;
>> + mp->log = NULL;
>> + init_waitqueue_head(&mp->wait);
>> +
>> return mp;
>> }
>>
>> @@ -663,6 +667,8 @@ struct metapage *__get_metapage(struct inode *inode, unsigned long lblock,
>> } else {
>> INCREMENT(mpStat.pagealloc);
>> mp = alloc_metapage(GFP_NOFS);
>> + if (!mp)
>> + goto unlock;
>> mp->page = page;
>> mp->sb = inode->i_sb;
>> mp->flag = 0;
>>
From 1582215076795154550@xxx Wed Oct 25 07:51:21 +0000 2017
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