Salut,
I've come upon a general bug in the implementation of the Linux Logos:
The logos themselves are defined as initdata, so they are no longer
availible when the system is started up. However, under certain
conditions, fbcon_init() is called when the system is already up, so
you get an oops. An example:
Unable to handle kernel paging request at virtual address c06a083c <- logo_linux_clut->height
printing eip:
c03a0207
*pde = 00103027
*pte = 006a0000
Oops: 0000 [#1]
CPU: 0
EIP: 0060:[<c03a0207>] Not tainted
EFLAGS: 00210282
EIP is at fb_prepare_logo+0x47/0xe0
eax: 00000300 ebx: d7768000 ecx: 00000000 edx: c06a0834 <- logo_linux_clut224
esi: d7768000 edi: 00000008 ebp: c06e48a4 esp: cdcb3d84
^^^^^^^^
con_driver_map[0]->con_init()
ds: 007b es: 007b ss: 0068
Process mplayer (pid: 10090, threadinfo=cdcb2000 task=cb466960)
Stack: 00000030 d42c4df8 c039cb31 d7768000 cfa86ef8 d796eeb0 c0196a52 d7ff9500
cdcb3e2c 00000030 00000080 00000001 00000000 c06ee9fc 00000100 00000080
00000030 d7768000 d42c4df8 00000001 c06e4784 c06e48a4 c039c63f d42c4df8
Call Trace:
[<c039cb31>] fbcon_set_display+0x4b1/0x760
[<c0196a52>] alloc_inode+0x152/0x160
[<c039c63f>] fbcon_init+0x3f/0x60
[<c0320642>] visual_init+0xa2/0x100
[<c0323dd1>] take_over_console+0x151/0x1c0
[<c039bdff>] set_con2fb_map+0x3f/0x60
[<c03a1119>] fb_ioctl+0x4b9/0x580
[<c0156ea9>] kmem_cache_alloc+0x129/0x1c0
[<c0310832>] down_tty_sem+0x12/0x40
[<c03108da>] init_dev+0x5a/0x4c0
[<c031b3a8>] vt_ioctl+0x1908/0x1fc0
[<c03239cf>] con_open+0xf/0x80
[<c0311a76>] tty_open+0x356/0x4a0
[<c0181bf4>] cp_new_stat64+0x114/0x140
[<c0181cca>] sys_fstat64+0x2a/0x40
[<c018c053>] sys_ioctl+0x1d3/0x3c0
[<c010b687>] syscall_call+0x7/0xb
Code: 39 42 08 76 14 b8 00 00 00 00 c7 05 50 fa 6e c0 00 00 00 00
Erreur de segmentation
This bug gets triggered every time one tries to use directfb. The
problem is that fb_prepare_logo() calls find_logo(), which returns the
pointer to the already freed linux_logo_clut224. Then
fb_prepare_logo() tries to access the height of the logo -> bang.
I'm not exactly sure how to solve this one. One solution is not to
make the logos initdata at all, another one is to return from
fb_prepare_logo() immediately if we are not in init code, though I'm
not exactly sure how to do that.
Tonnerre