[PATCH] riscv: elf: add .riscv.attributes parsing
Vineet Gupta
vineetg at rivosinc.com
Tue Jan 10 13:50:56 PST 2023
On 1/10/23 12:48, Jessica Clarke wrote:
> On 10 Jan 2023, at 20:18, Vineet Gupta <vineetg at rivosinc.com> wrote:
>> This implements the elf loader hook to parse RV specific
>> .riscv.attributes section. This section is inserted by compilers
>> (gcc/llvm) with build related information such as -march organized as
>> tag/value attribute pairs.
>>
>> It identifies the various attribute tags (and corresponding values) as
>> currently specified in the psABI specification.
>>
>> This patch only implements the elf parsing mechanics, leaving out the
>> recording/usage of the attributes to subsequent patches.
>>
>> Reported-by: kernel test robot <lkp at intel.com> # code under CONFIG_COMPAT
>> Signed-off-by: Vineet Gupta <vineetg at rivosinc.com>
> This code is full of buffer overruns and uninitialised reads in the
> presence of malicious files,
While the outer loop is bound, indeed the internal pointer increments
could get oob.
I don't recall seeing existing explicit "safe" pointer, so thinking of
cooking something up.
The conceptual idea is to replace
p += 4
with
PTR_INC(p, 4, p_max)
And similarly replace
while (*p++ != '\0')
with
while (*p != '\0')
PTR_INC(p, 1, p_max)
Is that sufficient or you had something else in mind.
> and fails to check the version, vendor and sub-subsection tag.
That is now added.
> You also should handle more than one sub-subsection even if tools don’t
> emit it today.
Just to be on same page, a sub-section implies the following
uint32:len, NTBS:vendor-name, uint8: Tag_file, uint32:data-len,
<tag><value>....
If so, the code does support multiple of these
> You also have an unaligned access for reading the sub-subsection’s data
> length (maybe that’s ok in kernel land, but worth making sure).
True, I've added get_unaligned_le32 for those now
Thx,
-Vineet
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