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kheaders: Use array declaration instead of char 

Under CONFIG_FORTIFY_SOURCE, memcpy() will check the size of destination
and source buffers. Defining kernel_headers_data as "char" would trip
this check. Since these addresses are treated as byte arrays, define
them as arrays (as done everywhere else).

This was seen with:

  $ cat /sys/kernel/kheaders.tar.xz >> /dev/null

  detected buffer overflow in memcpy
  kernel BUG at lib/string_helpers.c:1027!
  ...
  RIP: 0010:fortify_panic+0xf/0x20
  [...]
  Call Trace:
   <TASK>
   ikheaders_read+0x45/0x50 [kheaders]
   kernfs_fop_read_iter+0x1a4/0x2f0
  ...

Reported-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/bpf/20230302112130.6e402a98@kernel.org/
Acked-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Tested-by: Jakub Kicinski <kuba@kernel.org>
Fixes: 43d8ce9d65 ("Provide in-kernel headers to make extending kernel easier")
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230302224946.never.243-kees@kernel.org
This commit is contained in:
Kees Cook 2023-03-02 14:49:50 -08:00
parent eeac8ede17
commit b69edab47f
1 changed files with 5 additions and 5 deletions
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10
kernel/kheaders.c
View File

@ -26,15 +26,15 @@ asm (
" .popsection \n" " .popsection \n"
); );
extern char kernel_headers_data; extern char kernel_headers_data[];
extern char kernel_headers_data_end; extern char kernel_headers_data_end[];
static ssize_t static ssize_t
ikheaders_read(struct file *file, struct kobject *kobj, ikheaders_read(struct file *file, struct kobject *kobj,
struct bin_attribute *bin_attr, struct bin_attribute *bin_attr,
char *buf, loff_t off, size_t len) char *buf, loff_t off, size_t len)
{ {
memcpy(buf, &kernel_headers_data + off, len); memcpy(buf, &kernel_headers_data[off], len);
return len; return len;
} }
@ -48,8 +48,8 @@ static struct bin_attribute kheaders_attr __ro_after_init = {
static int __init ikheaders_init(void) static int __init ikheaders_init(void)
{ {
kheaders_attr.size = (&kernel_headers_data_end - kheaders_attr.size = (kernel_headers_data_end -
&kernel_headers_data); kernel_headers_data);
return sysfs_create_bin_file(kernel_kobj, &kheaders_attr); return sysfs_create_bin_file(kernel_kobj, &kheaders_attr);
} }