On 2020/07/14 16:22, Bartlomiej Zolnierkiewicz wrote: > How does this patch relate to: > > https://marc.info/?l=linux-fbdev&m=159415024816722&w=2 > > ? > > It seems to address the same issue, I've added George and Dan to Cc:. George Kennedy's patch does not help for my case. You can try a.out built from ---------- #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <sys/ioctl.h> #include <linux/fb.h> int main(int argc, char *argv[]) { const int fd = open("/dev/fb0", O_ACCMODE); struct fb_var_screeninfo var = { }; ioctl(fd, FBIOGET_VSCREENINFO, &var); var.xres = var.yres = 16; ioctl(fd, FBIOPUT_VSCREENINFO, &var); return 0; } ---------- with a fault injection patch ---------- --- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -1214,6 +1214,10 @@ static int vc_do_resize(struct tty_struct *tty, struct vc_data *vc, if (new_screen_size > KMALLOC_MAX_SIZE) return -EINVAL; + if (!strcmp(current->comm, "a.out")) { + printk(KERN_INFO "Forcing memory allocation failure.\n"); + return -ENOMEM; + } newscreen = kzalloc(new_screen_size, GFP_USER); if (!newscreen) return -ENOMEM; ---------- . What my patch workarounds is cases when vc_do_resize() did not update vc->vc_{cols,rows} . Unless vc->vc_{cols,rows} are updated by vc_do_resize() in a way that avoids integer underflow at unsigned int rw = info->var.xres - (vc->vc_cols*cw); unsigned int bh = info->var.yres - (vc->vc_rows*ch); , this crash won't go away. [ 39.995757][ T2788] Forcing memory allocation failure. [ 39.996527][ T2788] BUG: unable to handle page fault for address: ffffa9d180d7b000 [ 39.996529][ T2788] #PF: supervisor write access in kernel mode [ 39.996530][ T2788] #PF: error_code(0x0002) - not-present page [ 39.996531][ T2788] PGD 13a48c067 P4D 13a48c067 PUD 13a48d067 PMD 1324e4067 PTE 0 [ 39.996547][ T2788] Oops: 0002 [#1] SMP [ 39.996550][ T2788] CPU: 2 PID: 2788 Comm: a.out Not tainted 5.8.0-rc5+ #757 [ 39.996551][ T2788] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 02/27/2020 [ 39.996555][ T2788] RIP: 0010:bitfill_aligned+0x87/0x120 [cfbfillrect] _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
