From: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp
commit af77c56aa35325daa2bc2bed5c2ebf169be61b86 upstream.
syzbot reports kernel infoleak at vcs_read() [1], for buffer can be read immediately after resize operation. Initialize buffer using kzalloc().
---------- #include <fcntl.h> #include <unistd.h> #include <sys/ioctl.h> #include <linux/fb.h>
int main(int argc, char *argv[]) { struct fb_var_screeninfo var = { }; const int fb_fd = open("/dev/fb0", 3); ioctl(fb_fd, FBIOGET_VSCREENINFO, &var); var.yres = 0x21; ioctl(fb_fd, FBIOPUT_VSCREENINFO, &var); return read(open("/dev/vcsu", O_RDONLY), &var, sizeof(var)) == -1; } ----------
Link: https://syzkaller.appspot.com/bug?extid=31a641689d43387f05d3 [1] Cc: stable stable@vger.kernel.org Reported-by: syzbot syzbot+31a641689d43387f05d3@syzkaller.appspotmail.com Reviewed-by: Jiri Slaby jirislaby@kernel.org Signed-off-by: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp Link: https://lore.kernel.org/r/4ef053cf-e796-fb5e-58b7-3ae58242a4ad@I-love.SAKURA... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/tty/vt/vt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -351,7 +351,7 @@ static struct uni_screen *vc_uniscr_allo /* allocate everything in one go */ memsize = cols * rows * sizeof(char32_t); memsize += rows * sizeof(char32_t *); - p = vmalloc(memsize); + p = vzalloc(memsize); if (!p) return NULL;