wlr_output_get_primary_formats returning NULL not handled (causing segfault)

[sertonix]

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• Sway Version: 1.10

• Debug Log: sway.log

• Configuration File: xwayland disable

• Stack Trace: sway-bt.log

• Description:

If the wlroots documentation is correct wlr_output_get_primary_formats may return NULL (doc). It looks like this is not handled correctly at

sway/sway/config/output.c

Line 776 in f293418

wlr_output_get_primary_formats(wlr_output, WLR_BUFFER_CAP_DMABUF);

which passes the return value to wlr_drm_format_set_get without a NULL check. wlroots then tries to dereference the pointer and segfaults (drm_format_set.c#L32).

I wasn't able to create a reproducer that I can share but I hope the analysis is enough.

[emersion]

Indeed! We should add a NULL check right before wlr_drm_format_set_get(). Would you be willing to send a patch?

[sertonix]

I don't know in which line the NULL check belongs and what should be done in that case. So I would prefer to leave that to the experts. Hope that is ok.