os: Don't crash in AttendClient if the client is gone
If a client is in the process of being closed down, then its client->osPrivate pointer will be set to NULL by CloseDownConnection. This can cause a crash if freeing the client's resources results in a call to AttendClient. For example, if the client has a pending sync fence: Thread 1 "X" received signal SIGSEGV, Segmentation fault. AttendClient (client=0x5571c4aed9a0) at ../os/connection.c:942 (gdb) bt #0 AttendClient (client=0x5571c4aed9a0) at ../os/connection.c:942 #1 0x00005571c3dbb865 in SyncAwaitTriggerFired (pTrigger=<optimized out>) at ../Xext/sync.c:694 #2 0x00005571c3dd5749 in miSyncDestroyFence (pFence=0x5571c5063980) at ../miext/sync/misync.c:120 #3 0x00005571c3dbbc69 in FreeFence (obj=<optimized out>, id=<optimized out>) at ../Xext/sync.c:1909 #4 0x00005571c3d7a01d in doFreeResource (res=0x5571c506e3d0, skip=skip@entry=0) at ../dix/resource.c:880 #5 0x00005571c3d7b1dc in FreeClientResources (client=0x5571c4aed9a0) at ../dix/...
Showing with 12 additions and 12 deletions