Hi Greg,
below is the manual backport of an upstream patch to fix the build failure
in kernel v4.14 in imsttfb.c.
It's not sufficient to just return from init_imstt() as the kernel then
may crash later when it tries to access the non-existent framebuffer or
cmap. Instead return failure to imsttfb_probe() so that the kernel
will skip using that hardware/driver.
Can you please apply this patch to the v4.14 stable queue?
Thanks,
Helge
-----------
From: Zheng Wang <zyytlz.wz@xxxxxxx>
This is a manual backport of upstream patch c75f5a55061091030a13fef71b9995b89bc86213
to fix a build error in imsttfb.c in kernel v4.14.
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@xxxxxxx>
Signed-off-by: Helge Deller <deller@xxxxxx>
diff --git a/drivers/video/fbdev/imsttfb.c b/drivers/video/fbdev/imsttfb.c
index 6589d5f0a5a4..eaaa5f1c0f6f 100644
--- 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 *info)
|| !(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 *info)
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)
@@ -1474,6 +1475,7 @@ static int imsttfb_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
struct imstt_par *par;
struct fb_info *info;
struct device_node *dp;
+ int ret;
dp = pci_device_to_OF_node(pdev);
if(dp)
@@ -1525,10 +1527,10 @@ static int imsttfb_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
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)
