[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 9:12 PM, Mathieu Desnoyers mathieu.desnoyers at efficios.com wrote:

> ----- 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].

Actually, you should also state in this changelog that it fixes
a second issue: we lose the last element due to off-by-one on
index.

Thanks,

Mathieu

>> 
>> 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
>> 
>> _______________________________________________
>> lttng-dev mailing list
>> lttng-dev at lists.lttng.org
>> https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
> 
> --
> Mathieu Desnoyers
> EfficiOS Inc.
> http://www.efficios.com
> _______________________________________________
> lttng-dev mailing list
> lttng-dev at lists.lttng.org
> https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com