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video: fbdev: s3fb: Check the size of screen before memset_io()
[ Upstream commit6ba592fa01
] In the function s3fb_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: [ 54.083733] BUG: unable to handle page fault for address: ffffc90003000000 [ 54.083742] #PF: supervisor write access in kernel mode [ 54.083744] #PF: error_code(0x0002) - not-present page [ 54.083760] RIP: 0010:memset_orig+0x33/0xb0 [ 54.083782] Call Trace: [ 54.083788] s3fb_set_par+0x1ec6/0x4040 [ 54.083806] fb_set_var+0x604/0xeb0 [ 54.083836] do_fb_ioctl+0x234/0x670 Fix the this by checking the value of 'screen_size' before memset_io(). Fixes:a268422de8
("fbdev driver for S3 Trio/Virge") 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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@ -902,6 +902,8 @@ static int s3fb_set_par(struct fb_info *info)
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value = clamp((htotal + hsstart + 1) / 2 + 2, hsstart + 4, htotal + 1);
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svga_wcrt_multi(par->state.vgabase, s3_dtpc_regs, value);
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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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svga_wcrt_mask(par->state.vgabase, 0x17, 0x80, 0x80);
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