queue-6.6/of-module-prevent-null-pointer-dereference-in-vsnprintf.patch

   1 From a1aa5390cc912934fee76ce80af5f940452fa987 Mon Sep 17 00:00:00 2001
   2 From: Sergey Shtylyov <s.shtylyov@omp.ru>
   3 Date: Wed, 27 Mar 2024 19:52:49 +0300
   4 Subject: of: module: prevent NULL pointer dereference in vsnprintf()
   5
   6 From: Sergey Shtylyov <s.shtylyov@omp.ru>
   7
   8 commit a1aa5390cc912934fee76ce80af5f940452fa987 upstream.
   9
  10 In of_modalias(), we can get passed the str and len parameters which would
  11 cause a kernel oops in vsnprintf() since it only allows passing a NULL ptr
  12 when the length is also 0. Also, we need to filter out the negative values
  13 of the len parameter as these will result in a really huge buffer since
  14 snprintf() takes size_t parameter while ours is ssize_t...
  15
  16 Found by Linux Verification Center (linuxtesting.org) with the Svace static
  17 analysis tool.
  18
  19 Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
  20 Cc: stable@vger.kernel.org
  21 Link: https://lore.kernel.org/r/1d211023-3923-685b-20f0-f3f90ea56e1f@omp.ru
  22 Signed-off-by: Rob Herring <robh@kernel.org>
  23 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  24 ---
  25  drivers/of/module.c |    8 ++++++++
  26  1 file changed, 8 insertions(+)
  27
  28 --- a/drivers/of/module.c
  29 +++ b/drivers/of/module.c
  30 @@ -16,6 +16,14 @@ ssize_t of_modalias(const struct device_
  31         ssize_t csize;
  32         ssize_t tsize;
  33
  34 +       /*
  35 +        * Prevent a kernel oops in vsnprintf() -- it only allows passing a
  36 +        * NULL ptr when the length is also 0. Also filter out the negative
  37 +        * lengths...
  38 +        */
  39 +       if ((len > 0 && !str) || len < 0)
  40 +               return -EINVAL;
  41 +
  42         /* Name & Type */
  43         /* %p eats all alphanum characters, so %c must be used here */
  44         csize = snprintf(str, len, "of:N%pOFn%c%s", np, 'T',