[lttng-dev] [PATCH lttng-tools 1/2] Fix: syscall_table_nb_entry invalid value when no syscalls TPs are defined

[Mathieu Desnoyers]

----- On Mar 13, 2017, at 6:11 PM, Jonathan Rajotte jonathan.rajotte-julien at efficios.com wrote:

> fscanf on an empty file returns directly without assigning value to
> 'index' leading to assigning the value of an uninitialized variable to
> syscall_table_nb_entry. This can result in memory allocation problems
> when listing syscalls on 'lttng list --kernel --syscall'[1][2].
> 
> Fixes #1091
> 
> [1] https://bugs.lttng.org/issues/1091
> [2] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1671063/
> 
> Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien at efficios.com>
> ---
> src/bin/lttng-sessiond/syscall.c | 13 ++++++++++---
> 1 file changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/src/bin/lttng-sessiond/syscall.c b/src/bin/lttng-sessiond/syscall.c
> index 6ee38bd..c21e4d8 100644
> --- a/src/bin/lttng-sessiond/syscall.c
> +++ b/src/bin/lttng-sessiond/syscall.c
> @@ -16,6 +16,8 @@
>  */
> 
> #define _LGPL_SOURCE
> +#include <stdbool.h>
> +
> #include <common/bitfield.h>
> #include <common/common.h>
> #include <common/kernel-ctl/kernel-ctl.h>
> @@ -43,7 +45,8 @@ int syscall_init_table(void)
> 	size_t nbmem;
> 	FILE *fp;
> 	/* Syscall data from the kernel. */
> -	size_t index;
> +	size_t index = 0;
> +	bool at_least_one_syscall = false;
> 	uint32_t bitness;
> 	char name[SYSCALL_NAME_LEN];
> 
> @@ -76,7 +79,8 @@ int syscall_init_table(void)
> 				name = %" XSTR(SYSCALL_NAME_LEN) "[^;]; \
> 				bitness = %u; };\n",
> 				&index, name, &bitness) == 3) {
> -		if (index >= nbmem ) {
> +		at_least_one_syscall = true;
> +		if (index >= nbmem) {
> 			struct syscall *new_list;
> 			size_t new_nbmem;
> 
> @@ -123,7 +127,10 @@ int syscall_init_table(void)
> 		*/
> 	}
> 
> -	syscall_table_nb_entry = index;
> +	/* Index start at 0. */

start -> starts

other than that:

Acked-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>

> +	if (at_least_one_syscall) {
> +		syscall_table_nb_entry = index + 1;
> +	}
> 
> 	ret = 0;
> 
> --
> 2.7.4
> 
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> lttng-dev at lists.lttng.org
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-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com