--- /dev/null
+From c75f5a55061091030a13fef71b9995b89bc86213 Mon Sep 17 00:00:00 2001
+From: Zheng Wang <zyytlz.wz@163.com>
+Date: Thu, 27 Apr 2023 11:08:41 +0800
+Subject: fbdev: imsttfb: Fix use after free bug in imsttfb_probe
+
+From: Zheng Wang <zyytlz.wz@163.com>
+
+commit c75f5a55061091030a13fef71b9995b89bc86213 upstream.
+
+A use-after-free bug may occur if init_imstt invokes framebuffer_release
+and free the info ptr. The caller, imsttfb_probe didn't notice that and
+still keep the ptr as private data in pdev.
+
+If we remove the driver which will call imsttfb_remove to make cleanup,
+UAF happens.
+
+Fix it by return error code if bad case happens in init_imstt.
+
+Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
+Signed-off-by: Helge Deller <deller@gmx.de>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ drivers/video/fbdev/imsttfb.c | 18 ++++++++++--------
+ 1 file changed, 10 insertions(+), 8 deletions(-)
+
+--- a/drivers/video/fbdev/imsttfb.c
++++ b/drivers/video/fbdev/imsttfb.c
+@@ -1348,7 +1348,7 @@ static struct fb_ops imsttfb_ops = {
+ .fb_ioctl = imsttfb_ioctl,
+ };
+
+-static void init_imstt(struct fb_info *info)
++static int init_imstt(struct fb_info *info)
+ {
+ struct imstt_par *par = info->par;
+ __u32 i, tmp, *ip, *end;
+@@ -1420,7 +1420,7 @@ static void init_imstt(struct fb_info *i
+ || !(compute_imstt_regvals(par, info->var.xres, info->var.yres))) {
+ printk("imsttfb: %ux%ux%u not supported\n", info->var.xres, info->var.yres, info->var.bits_per_pixel);
+ framebuffer_release(info);
+- return;
++ return -ENODEV;
+ }
+
+ sprintf(info->fix.id, "IMS TT (%s)", par->ramdac == IBM ? "IBM" : "TVP");
+@@ -1460,12 +1460,13 @@ static void init_imstt(struct fb_info *i
+ if (register_framebuffer(info) < 0) {
+ fb_dealloc_cmap(&info->cmap);
+ framebuffer_release(info);
+- return;
++ return -ENODEV;
+ }
+
+ tmp = (read_reg_le32(par->dc_regs, SSTATUS) & 0x0f00) >> 8;
+ fb_info(info, "%s frame buffer; %uMB vram; chip version %u\n",
+ info->fix.id, info->fix.smem_len >> 20, tmp);
++ return 0;
+ }
+
+ static int imsttfb_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
+@@ -1474,7 +1475,8 @@ static int imsttfb_probe(struct pci_dev
+ struct imstt_par *par;
+ struct fb_info *info;
+ struct device_node *dp;
+-
++ int ret;
++
+ dp = pci_device_to_OF_node(pdev);
+ if(dp)
+ printk(KERN_INFO "%s: OF name %s\n",__func__, dp->name);
+@@ -1525,10 +1527,10 @@ static int imsttfb_probe(struct pci_dev
+ par->cmap_regs_phys = addr + 0x840000;
+ par->cmap_regs = (__u8 *)ioremap(addr + 0x840000, 0x1000);
+ info->pseudo_palette = par->palette;
+- init_imstt(info);
+-
+- pci_set_drvdata(pdev, info);
+- return 0;
++ ret = init_imstt(info);
++ if (!ret)
++ pci_set_drvdata(pdev, info);
++ return ret;
+ }
+
+ static void imsttfb_remove(struct pci_dev *pdev)