Hi James,
I have few problems with understanding how
info->cmap is supposed to work:
(1) FBIOGETCMAP calls fb_copy_cmap(&info->cmap, &cmap, 0);
Should not it use last argument of '2', as &cmap points
to the userspace? It looks to me like that anybody can
overwrite kernel currently... Only positive side is that
there is no way to control info->cmap contents (see (2)),
so you can only crash kernel with random code, you cannot
stuff some malicious code there.
(2) FBIOPUTCMAP calls fb_set_cmap, which in turn calls
fb_setcolreg. FBIOGETCMAP copies cmap entries from
info->cmap (after fixing (1)). Does it mean that
fb_setcolreg has to fill info->cmap itself? Is not it
a bit ugly? And fb_set_cmap documentation is incorrect:
kspc == 0 means copy from userspace, while
kspc != 0 means copy "local", inside kernel-space. Documentation
says that 0 is local, while 1 is get_user.
(3) And who is supposed to initialize info->cmap, and to
what value? It looks to me like that fbdev driver is
supposed to do:
memset(&info->cmap, 0, sizeof(info->cmap));
fb_alloc_cmap(&info->cmap, 256, 1);
Is it right? What about fb_init_cmap() then? And why
fbdev has to play with info->cmap, cannot generic
layer take a care of this, if all info->cmap accesses
go through generic layer, and fbdev driver itself has
no need for this field?
Thanks,
Petr Vandrovec
vandrove@vc.cvut.cz
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This archive was generated by hypermail 2b29 : Wed Jul 23 2003 - 22:00:43 EST