On 3/2/22 15:33, Zheyu Ma wrote: > When the sm712fb driver writes three bytes to the framebuffer, the > driver will crash: > > BUG: unable to handle page fault for address: ffffc90001ffffff > RIP: 0010:smtcfb_write+0x454/0x5b0 > Call Trace: > vfs_write+0x291/0xd60 > ? do_sys_openat2+0x27d/0x350 > ? __fget_light+0x54/0x340 > ksys_write+0xce/0x190 > do_syscall_64+0x43/0x90 > entry_SYSCALL_64_after_hwframe+0x44/0xae > > Fix it by removing the open-coded endianness fixup-code. > > Signed-off-by: Zheyu Ma <zheyuma97@xxxxxxxxx> Thanks... it's already in the fbdev git tree and queued up for v5.18... https://git.kernel.org/pub/scm/linux/kernel/git/deller/linux-fbdev.git/commit/?h=for-next&id=bd771cf5c4254511cc4abb88f3dab3bd58bdf8e8 Helge > --- > drivers/video/fbdev/sm712fb.c | 21 ++++----------------- > 1 file changed, 4 insertions(+), 17 deletions(-) > > diff --git a/drivers/video/fbdev/sm712fb.c b/drivers/video/fbdev/sm712fb.c > index 0dbc6bf8268a..e355089ac7d6 100644 > --- a/drivers/video/fbdev/sm712fb.c > +++ b/drivers/video/fbdev/sm712fb.c > @@ -1130,7 +1130,7 @@ static ssize_t smtcfb_write(struct fb_info *info, const char __user *buf, > count = total_size - p; > } > > - buffer = kmalloc((count > PAGE_SIZE) ? PAGE_SIZE : count, GFP_KERNEL); > + buffer = kmalloc(PAGE_SIZE, GFP_KERNEL); > if (!buffer) > return -ENOMEM; > > @@ -1148,24 +1148,11 @@ static ssize_t smtcfb_write(struct fb_info *info, const char __user *buf, > break; > } > > - for (i = c >> 2; i--;) { > - fb_writel(big_swap(*src), dst++); > + for (i = (c + 3) >> 2; i--;) { > + fb_writel(big_swap(*src), dst); > + dst++; > src++; > } > - if (c & 3) { > - u8 *src8 = (u8 *)src; > - u8 __iomem *dst8 = (u8 __iomem *)dst; > - > - for (i = c & 3; i--;) { > - if (i & 1) { > - fb_writeb(*src8++, ++dst8); > - } else { > - fb_writeb(*src8++, --dst8); > - dst8 += 2; > - } > - } > - dst = (u32 __iomem *)dst8; > - } > > *ppos += c; > buf += c;
