Messages in this thread | | | Date | Mon, 22 Jun 2020 21:31:09 +0200 | From | Greg Kroah-Hartman <> | Subject | Re: debugfs_create_u32_array() memory leaks |
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On Mon, Jun 22, 2020 at 12:23:32PM -0700, Jakub Kicinski wrote: > On Sat, 20 Jun 2020 09:45:42 +0200 Greg Kroah-Hartman wrote: > > On Fri, Jun 19, 2020 at 04:17:34PM -0700, Jakub Kicinski wrote: > > > Hi! > > > > > > I'm trying to use debugfs_create_u32_array() in drivers/net/netdevsim > > > and it causes memory leaks: > > > > > > unreferenced object 0xffff8880546642a0 (size 16): > > > comm "test_udp_tuns.s", pid 2146, jiffies 4294928368 (age 3772.435s) > > > hex dump (first 16 bytes): > > > 84 52 6a 4d 80 88 ff ff 04 00 00 00 f3 78 7e 89 .RjM.........x~. > > > backtrace: > > > [<000000006962a447>] debugfs_create_u32_array+0x3f/0x90 > > > > > > I can see that debugfs_create_u32_array() allocates a structure at > > > create time that ends up assigned to inode->i_private, but I don't > > > see it freed anywhere. > > > > > > Am I missing something? I'm pretty sure files get removed, cause the > > > driver calls debugfs_remove_recursive() and no other file types leaks. > > > > Yeah, that's a bug, nice catch. The debugfs_create*() functions should > > not allocate local memory as we can't know to free that memory when the > > file is removed. > > > > Can you fix this up, or do you want me to? I only see one in-kernel > > user of this, so it shouldn't be that tough to do so. The one user > > never removes that file so that's why no one noticed this before. > > Ah, I wasn't sure how to fix but since you say that create functions > shouldn't allocate memory seems like the fix will be to make callers > pass an equivalent of struct debugfs_blob_wrapper for u32.
Sounds good.
> I'm happy to send a patch to that effect - I have a process question > tho - I need this change in net-next, should I sent the patch to you? > Can it still make it into 5.8 (debugfs -> Linus -> net -> net-next) or > perhaps can it go via net-next since there is no de facto bug in 5.8?
I can take a fix now, and get it into 5.8 if that makes things easier for you.
thanks,
greg k-h
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