diff options
| author | Helge Deller | 2022-02-27 08:43:56 +0100 |
|---|---|---|
| committer | Helge Deller | 2022-02-27 08:43:56 +0100 |
| commit | bd771cf5c4254511cc4abb88f3dab3bd58bdf8e8 (patch) | |
| tree | 21186273f7b32374c7605edf9c85afbe3c9403bb /drivers/video/fbdev | |
| parent | 997403e7782a3b9aa6e2b28c6b78793659483af3 (diff) | |
video: fbdev: sm712fb: Fix crash in smtcfb_read()
Zheyu Ma reported this crash in the sm712fb driver when reading
three bytes from the framebuffer:
BUG: unable to handle page fault for address: ffffc90001ffffff
RIP: 0010:smtcfb_read+0x230/0x3e0
Call Trace:
vfs_read+0x198/0xa00
? do_sys_openat2+0x27d/0x350
? __fget_light+0x54/0x340
ksys_read+0xce/0x190
do_syscall_64+0x43/0x90
Fix it by removing the open-coded endianess fixup-code and
by moving the pointer post decrement out the fb_readl() function.
Reported-by: Zheyu Ma <zheyuma97@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>
Tested-by: Zheyu Ma <zheyuma97@gmail.com>
Cc: stable@vger.kernel.org
Diffstat (limited to 'drivers/video/fbdev')
| -rw-r--r-- | drivers/video/fbdev/sm712fb.c | 25 |
1 files changed, 7 insertions, 18 deletions
diff --git a/drivers/video/fbdev/sm712fb.c b/drivers/video/fbdev/sm712fb.c index 0dbc6bf8268a..b60a2730f0a8 100644 --- a/drivers/video/fbdev/sm712fb.c +++ b/drivers/video/fbdev/sm712fb.c @@ -1047,7 +1047,7 @@ static ssize_t smtcfb_read(struct fb_info *info, char __user *buf, if (count + p > total_size) count = total_size - p; - buffer = kmalloc((count > PAGE_SIZE) ? PAGE_SIZE : count, GFP_KERNEL); + buffer = kmalloc(PAGE_SIZE, GFP_KERNEL); if (!buffer) return -ENOMEM; @@ -1059,24 +1059,13 @@ static ssize_t smtcfb_read(struct fb_info *info, char __user *buf, while (count) { c = (count > PAGE_SIZE) ? PAGE_SIZE : count; dst = buffer; - for (i = c >> 2; i--;) { - *dst = fb_readl(src++); - *dst = big_swap(*dst); - dst++; - } - if (c & 3) { - u8 *dst8 = (u8 *)dst; - u8 __iomem *src8 = (u8 __iomem *)src; + for (i = (c + 3) >> 2; i--;) { + u32 val; - for (i = c & 3; i--;) { - if (i & 1) { - *dst8++ = fb_readb(++src8); - } else { - *dst8++ = fb_readb(--src8); - src8 += 2; - } - } - src = (u32 __iomem *)src8; + val = fb_readl(src); + *dst = big_swap(val); + src++; + dst++; } if (copy_to_user(buf, buffer, c)) { |