lkml.org 
[lkml]   [2022]   [Apr]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5.15 143/913] video: fbdev: sm712fb: Fix crash in smtcfb_read()
    Date
    From: Helge Deller <deller@gmx.de>

    commit bd771cf5c4254511cc4abb88f3dab3bd58bdf8e8 upstream.

    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
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/video/fbdev/sm712fb.c | 25 +++++++------------------
    1 file changed, 7 insertions(+), 18 deletions(-)

    --- a/drivers/video/fbdev/sm712fb.c
    +++ b/drivers/video/fbdev/sm712fb.c
    @@ -1047,7 +1047,7 @@ static ssize_t smtcfb_read(struct fb_inf
    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;

    @@ -1059,25 +1059,14 @@ static ssize_t smtcfb_read(struct fb_inf
    while (count) {
    c = (count > PAGE_SIZE) ? PAGE_SIZE : count;
    dst = buffer;
    - for (i = c >> 2; i--;) {
    - *dst = fb_readl(src++);
    - *dst = big_swap(*dst);
    + for (i = (c + 3) >> 2; i--;) {
    + u32 val;
    +
    + val = fb_readl(src);
    + *dst = big_swap(val);
    + src++;
    dst++;
    }
    - if (c & 3) {
    - u8 *dst8 = (u8 *)dst;
    - u8 __iomem *src8 = (u8 __iomem *)src;
    -
    - for (i = c & 3; i--;) {
    - if (i & 1) {
    - *dst8++ = fb_readb(++src8);
    - } else {
    - *dst8++ = fb_readb(--src8);
    - src8 += 2;
    - }
    - }
    - src = (u32 __iomem *)src8;
    - }

    if (copy_to_user(buf, buffer, c)) {
    err = -EFAULT;

    \
     
     \ /
      Last update: 2022-04-05 16:42    [W:4.024 / U:0.164 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site