target/linux/generic/backport-5.10/803-v5.13-0005-nvmem-core-Fix-unintentional-sign-extension-issue.patch

   1 From 55022fdeace8e432f008787ce03703bdcc9c3ca9 Mon Sep 17 00:00:00 2001
   2 From: Colin Ian King <colin.king@canonical.com>
   3 Date: Tue, 30 Mar 2021 12:12:38 +0100
   4 Subject: [PATCH] nvmem: core: Fix unintentional sign extension issue
   5
   6 The shifting of the u8 integer buf[3] by 24 bits to the left will
   7 be promoted to a 32 bit signed int and then sign-extended to a
   8 u64. In the event that the top bit of buf[3] is set then all
   9 then all the upper 32 bits of the u64 end up as also being set
  10 because of the sign-extension. Fix this by casting buf[i] to
  11 a u64 before the shift.
  12
  13 Fixes: a28e824fb827 ("nvmem: core: Add functions to make number reading easy")
  14 Reviewed-by: Douglas Anderson <dianders@chromium.org>
  15 Signed-off-by: Colin Ian King <colin.king@canonical.com>
  16 Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
  17 Addresses-Coverity: ("Unintended sign extension")
  18 Link: https://lore.kernel.org/r/20210330111241.19401-8-srinivas.kandagatla@linaro.org
  19 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  20 ---
  21  drivers/nvmem/core.c | 2 +-
  22  1 file changed, 1 insertion(+), 1 deletion(-)
  23
  24 --- a/drivers/nvmem/core.c
  25 +++ b/drivers/nvmem/core.c
  26 @@ -1699,7 +1699,7 @@ int nvmem_cell_read_variable_le_u64(stru
  27         /* Copy w/ implicit endian conversion */
  28         *val = 0;
  29         for (i = 0; i < len; i++)
  30 -               *val |= buf[i] << (8 * i);
  31 +               *val |= (uint64_t)buf[i] << (8 * i);
  32
  33         kfree(buf);
  34