linux-kernel - Re: [PATCH v4 10/13] selftests/sgx: Fix uninitialized pointer dereferences

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Message-Id: <CV3JM96HKCU0.2ZSE4CAS0QV9A@suppilovahvero>
Date:   Sun, 27 Aug 2023 21:36:22 +0300
From:   "Jarkko Sakkinen" <jarkko@...nel.org>
To:     "Jo Van Bulck" <jo.vanbulck@...kuleuven.be>, <kai.huang@...el.com>,
        <linux-sgx@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Cc:     <dave.hansen@...ux.intel.com>
Subject: Re: [PATCH v4 10/13] selftests/sgx: Fix uninitialized pointer
 dereferences

On Fri Aug 25, 2023 at 4:32 PM EEST, Jo Van Bulck wrote:
> Ensure sym_tab and sym_names are zero-initialized and add an early-out
> condition in the unlikely (erroneous) case that the enclave ELF file would
> not contain a symbol table.
>
> This addresses -Werror=maybe-uninitialized compiler warnings for gcc -O2.
>
> Fixes: 33c5aac3bf32 ("selftests/sgx: Test complete changing of page type flow")
> Signed-off-by: Jo Van Bulck <jo.vanbulck@...kuleuven.be>
> ---
>  tools/testing/selftests/sgx/load.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/tools/testing/selftests/sgx/load.c b/tools/testing/selftests/sgx/load.c
> index 94bdeac1cf04..c9f658e44de6 100644
> --- a/tools/testing/selftests/sgx/load.c
> +++ b/tools/testing/selftests/sgx/load.c
> @@ -136,11 +136,11 @@ static bool encl_ioc_add_pages(struct encl *encl, struct encl_segment *seg)
>   */
>  uint64_t encl_get_entry(struct encl *encl, const char *symbol)
>  {
> +	Elf64_Sym *symtab = NULL;
> +	char *sym_names = NULL;
>  	Elf64_Shdr *sections;
> -	Elf64_Sym *symtab;
>  	Elf64_Ehdr *ehdr;
> -	char *sym_names;
> -	int num_sym;
> +	int num_sym = 0;
>  	int i;
>  
>  	ehdr = encl->bin;
> @@ -161,6 +161,9 @@ uint64_t encl_get_entry(struct encl *encl, const char *symbol)
>  		}
>  	}
>  
> +	if (!symtab || !sym_names)
> +		return 0;
> +
>  	for (i = 0; i < num_sym; i++) {
>  		Elf64_Sym *sym = &symtab[i];
>  
> -- 
> 2.25.1

Bug fixes should be always in the head of the patch set.

BR, Jarkko