Re: [PATCH] nvme-multipath: Fix memory leak with ana_log_buf

[Keith Busch]

On Thu, Feb 20, 2020 at 01:29:53PM -0700, Logan Gunthorpe wrote:
> kmemleak reports a memory leak with the ana_log_buf allocated by
> nvme_mpath_init():
> 
> unreferenced object 0xffff888120e94000 (size 8208):
>   comm "nvme", pid 6884, jiffies 4295020435 (age 78786.312s)
>     hex dump (first 32 bytes):
>       00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00  ................
>       01 00 00 00 01 00 00 00 00 00 00 00 00 00 00 00  ................
>     backtrace:
>       [<00000000e2360188>] kmalloc_order+0x97/0xc0
>       [<0000000079b18dd4>] kmalloc_order_trace+0x24/0x100
>       [<00000000f50c0406>] __kmalloc+0x24c/0x2d0
>       [<00000000f31a10b9>] nvme_mpath_init+0x23c/0x2b0
>       [<000000005802589e>] nvme_init_identify+0x75f/0x1600
>       [<0000000058ef911b>] nvme_loop_configure_admin_queue+0x26d/0x280
>       [<00000000673774b9>] nvme_loop_create_ctrl+0x2a7/0x710
>       [<00000000f1c7a233>] nvmf_dev_write+0xc66/0x10b9
>       [<000000004199f8d0>] __vfs_write+0x50/0xa0
>       [<0000000065466fef>] vfs_write+0xf3/0x280
>       [<00000000b0db9a8b>] ksys_write+0xc6/0x160
>       [<0000000082156b91>] __x64_sys_write+0x43/0x50
>       [<00000000c34fbb6d>] do_syscall_64+0x77/0x2f0
>       [<00000000bbc574c9>] entry_SYSCALL_64_after_hwframe+0x49/0xbe
> 
> nvme_mpath_init() is called by nvme_init_identify() which is called in
> multiple places (nvme_reset_work(), nvme_passthru_end(), etc). This
> means nvme_mpath_init() may be called multiple times before
> nvme_mpath_uninit() (which is only called on nvme_free_ctrl()).
> 
> When nvme_mpath_init() is called multiple times, it overwrites the
> ana_log_buf pointer with a new allocation, thus leaking the previous
> allocation.
> 
> To fix this, free ana_log_buf before allocating a new one.
> 
> Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>

Thanks, applied to 5.6-rc3 with the reviews and the fixes tag.