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video: fbdev: vt8623fb: Check the size of screen before memset_io()
[ Upstream commitec0754c602
] In the function vt8623fb_set_par(), the value of 'screen_size' is calculated by the user input. If the user provides the improper value, the value of 'screen_size' may larger than 'info->screen_size', which may cause the following bug: [ 583.339036] BUG: unable to handle page fault for address: ffffc90005000000 [ 583.339049] #PF: supervisor write access in kernel mode [ 583.339052] #PF: error_code(0x0002) - not-present page [ 583.339074] RIP: 0010:memset_orig+0x33/0xb0 [ 583.339110] Call Trace: [ 583.339118] vt8623fb_set_par+0x11cd/0x21e0 [ 583.339146] fb_set_var+0x604/0xeb0 [ 583.339181] do_fb_ioctl+0x234/0x670 [ 583.339209] fb_ioctl+0xdd/0x130 Fix the this by checking the value of 'screen_size' before memset_io(). Fixes:558b7bd86c
("vt8623fb: new framebuffer driver for VIA VT8623") Signed-off-by: Zheyu Ma <zheyuma97@gmail.com> Signed-off-by: Helge Deller <deller@gmx.de> Signed-off-by: Sasha Levin <sashal@kernel.org>
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@ -507,6 +507,8 @@ static int vt8623fb_set_par(struct fb_info *info)
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(info->var.vmode & FB_VMODE_DOUBLE) ? 2 : 1, 1,
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1, info->node);
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if (screen_size > info->screen_size)
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screen_size = info->screen_size;
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memset_io(info->screen_base, 0x00, screen_size);
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/* Device and screen back on */
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