From: Michael Jeanson Date: Thu, 23 Mar 2023 16:45:18 +0000 (-0400) Subject: Fix: truncated len in lttng_event_rule_user_tracepoint_serialize() X-Git-Url: https://git.liburcu.org/?a=commitdiff_plain;h=7cb804198ecae54f791b76db058916c3cf2c48d9;hp=7cb804198ecae54f791b76db058916c3cf2c48d9;p=lttng-tools.git Fix: truncated len in lttng_event_rule_user_tracepoint_serialize() Observed issue ============== On 64-bit big-endian platforms, the serialization/deserialization tests of tracepoint event rules fail since the length of individual exclusions is truncated in lttng_event_rule_user_tracepoint_serialize and appear as "0" on the receiving end. Cause ===== The length of the exclusion name string is stored in a variable of type `size_t`. However, since the protocol expects it to be expressed as a uint32_t, the value is added to the payload by copying the first 4 bytes of the value. On a 32-bit system this would be fine since `sizeof(size_t) == 4`. Even worse, it would work most of the time (assuming an exclusion name string < 4GiB) on a little-endian 64-bit system as the least significant bits would be copied and correctly express the length of the string. On a big-endian 64-bit platform, the most-significant 4 bytes are copied to the payload buffer thus making the string length appear as "0". Solution ======== A temporary variable is used to hold the "casted" value and make it safe to copy to the payload buffer regardless of the platform's endianness. Known drawbacks =============== None. Change-Id: I64c03345fff7ffea2f8fcb84692a085da31c421b Signed-off-by: Michael Jeanson Signed-off-by: Jérémie Galarneau ---