glamor_create_pixmap() would return a NullPixmap if the given size is
larger than the maximum size of a pixmap.
But glamor_get_pixmap_texture() won't check if the given pixmap is
non-null, leading to a segfault if glamor_create_pixmap() failed.
This can be reproduced by passing Xephyr a very large screen width,
e.g.:
$ Xephyr -glamor -screen 32768x1024 :10
(EE)
(EE) Backtrace:
(EE) 0: Xephyr (OsSigHandler+0x29)
(EE) 1: /lib64/libpthread.so.0 (__restore_rt+0x0)
(EE) 2: Xephyr (glamor_get_pixmap_texture+0x30)
(EE) 3: Xephyr (ephyr_glamor_create_screen_resources+0xc6)
(EE) 4: Xephyr (ephyrCreateResources+0x98)
(EE) 5: Xephyr (dix_main+0x275)
(EE) 6: /lib64/libc.so.6 (__libc_start_main+0xf1)
(EE) 7: Xephyr (_start+0x2a)
(EE) 8: ? (?+0x2a) [0x2a]
(EE)
(EE) Segmentation fault at address 0x0
(EE)
Fatal server error:
(EE) Caught signal 11 (Segmentation fault). Server aborting
(EE)
Aborted (core dumped)
Bugzilla: https://bugzilla.redhat.com/1431633
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
f40ff18c96