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vgacon: Prevent faulty bootparams.screeninfo from causing harm
If a zero for the number of colums or rows manages to slip through, gotoxy() will underflow vc->vc_pos, causing the next action on the referenced memory to end with a page fault. Make the check in vgacon_startup() more pessimistic to prevent that. Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
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@ -398,9 +398,8 @@ static const char *vgacon_startup(void)
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#endif
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}
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/* boot_params.screen_info initialized? */
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if ((screen_info.orig_video_mode == 0) &&
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(screen_info.orig_video_lines == 0) &&
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/* boot_params.screen_info reasonably initialized? */
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if ((screen_info.orig_video_lines == 0) ||
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(screen_info.orig_video_cols == 0))
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goto no_vga;
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