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video: fbdev: sm712fb: Fix crash in smtcfb_write()

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[ Upstream commit 4f01d09b2b ]

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@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Zheyu Ma 2022-03-02 22:33:11 +08:00 committed by Greg Kroah-Hartman
parent e7bb29df2a
commit b1c2857752
1 changed files with 4 additions and 17 deletions
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21
drivers/video/fbdev/sm712fb.c
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@ -1119,7 +1119,7 @@ static ssize_t smtcfb_write(struct fb_info *info, const char __user *buf,
count = total_size - p; count = total_size - p;
} }
buffer = kmalloc((count > PAGE_SIZE) ? PAGE_SIZE : count, GFP_KERNEL); buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (!buffer) if (!buffer)
return -ENOMEM; return -ENOMEM;
@ -1137,24 +1137,11 @@ static ssize_t smtcfb_write(struct fb_info *info, const char __user *buf,
break; break;
} }
for (i = c >> 2; i--;) { for (i = (c + 3) >> 2; i--;) {
fb_writel(big_swap(*src), dst++); fb_writel(big_swap(*src), dst);
dst++;
src++; 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; *ppos += c;
buf += c; buf += c;