4.18.16: memory leak in sta_set_sinfo

[Johannes Stezenbach <js@xxxxxxxxx>]

Hi,

I used 4.18.11 for a while and noticed a memleak showing
in slabtop as kmalloc-2048.  Then I updated to 4.18.16
and enabled kmemleak, it dumps this:

unreferenced object 0xffffa10a5cc49800 (size 2048):
  comm "conky", pid 2734, jiffies 4295635396 (age 454.650s)
  hex dump (first 32 bytes):
    1e 00 00 00 00 00 00 00 ad 13 00 00 00 00 00 00  ................
    a1 0d 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<00000000b7b13d1a>] sta_set_sinfo+0x634/0x900 [mac80211]
    [<00000000a74db622>] ieee80211_get_station+0x50/0x70 [mac80211]
    [<0000000039cfbb15>] cfg80211_wireless_stats+0x103/0x350 [cfg80211]
    [<000000003e9c0192>] iw_handler_get_iwstats+0x3b/0x90
    [<0000000058160332>] ioctl_standard_iw_point+0xef/0x370
    [<000000008af7fc78>] ioctl_standard_call+0x9d/0xb0
    [<000000009ad7a410>] wext_handle_ioctl+0x99/0xf0
    [<000000006bc483dc>] sock_ioctl+0x1b5/0x330
    [<000000004a40c83b>] do_vfs_ioctl+0xa4/0x620
    [<00000000c498918f>] ksys_ioctl+0x3a/0x70
    [<00000000033ccded>] __x64_sys_ioctl+0x16/0x20
    [<0000000038d98ffe>] do_syscall_64+0x56/0x110
    [<00000000913ebc09>] entry_SYSCALL_64_after_hwframe+0x49/0xbe
    [<00000000b4781b29>] 0xffffffffffffffff
unreferenced object 0xffffa10a5cc4c000 (size 2048):
  comm "conky", pid 2734, jiffies 4295635396 (age 454.650s)
  hex dump (first 32 bytes):
    1e 00 00 00 00 00 00 00 ad 13 00 00 00 00 00 00  ................
    a1 0d 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<00000000b7b13d1a>] sta_set_sinfo+0x634/0x900 [mac80211]
    [<00000000a74db622>] ieee80211_get_station+0x50/0x70 [mac80211]
    [<000000009fd8a7aa>] cfg80211_wext_giwrate+0x111/0x2b0 [cfg80211]
    [<0000000045f8e84f>] ioctl_standard_call+0x4d/0xb0
    [<000000009ad7a410>] wext_handle_ioctl+0x99/0xf0
    [<000000006bc483dc>] sock_ioctl+0x1b5/0x330
    [<000000004a40c83b>] do_vfs_ioctl+0xa4/0x620
    [<00000000c498918f>] ksys_ioctl+0x3a/0x70
    [<00000000033ccded>] __x64_sys_ioctl+0x16/0x20
    [<0000000038d98ffe>] do_syscall_64+0x56/0x110
    [<00000000913ebc09>] entry_SYSCALL_64_after_hwframe+0x49/0xbe
    [<00000000b4781b29>] 0xffffffffffffffff

etc.

sta_set_sinfo+0x634/0x900 seemt to be the call to
cfg80211_sinfo_alloc_tid_stats().


dmesg:

[ 2975.537043] kmemleak: 1223 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
[ 3140.960503] kmemleak: 851 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
[ 3755.462385] kmemleak: 280 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
[ 4369.876913] kmemleak: 1011 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
[ 4984.711904] kmemleak: 1002 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
[ 5598.838136] kmemleak: 1023 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
[ 6213.236272] kmemleak: 1088 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
[ 6833.692160] kmemleak: 1004 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
[ 7447.151259] kmemleak: 1147 new suspected memory leaks (see /sys/kernel/debug/kmemleak)

I guess it relates to
0fdf1493b41 " mac80211: allocate and fill tidstats only when needed"
which Fixes: 8689c051a201 ("cfg80211: dynamically allocate per-tid stats for station info")


Johannes