[lttng-dev] [PATCH v3 lttng-tools] Fix: Accept bytecode of length 65536 bytes

[Christian Babeux]

In order to support the filter bytecode maximum length (65536 bytes),
the lttng_ust_filter_bytecode len field type must be able to
hold more than a uint16_t. Change the field type to a uint32_t.

Also, since the relocation table is located at the end of the actual
bytecode, the reloc_table_offset (reloc_offset in ust-abi) field must
support offset values larger than 65535. Change the field type to a
uint32_t. This change will allow support of relocation table appended
to larger bytecode without breaking the ABI if the need arise in the
future.

Both changes currently breaks the filter ABI, but this should be a
reasonable compromise since the filtering feature has not been
released yet.

Signed-off-by: Christian Babeux <christian.babeux at efficios.com>
---
 src/bin/lttng-sessiond/lttng-ust-abi.h                      | 6 +++---
 src/bin/lttng-sessiond/main.c                               | 2 +-
 src/common/sessiond-comm/sessiond-comm.h                    | 6 +++---
 src/lib/lttng-ctl/filter/filter-visitor-generate-bytecode.c | 2 +-
 4 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/bin/lttng-sessiond/lttng-ust-abi.h b/src/bin/lttng-sessiond/lttng-ust-abi.h
index d8b10c2..504c060 100644
--- a/src/bin/lttng-sessiond/lttng-ust-abi.h
+++ b/src/bin/lttng-sessiond/lttng-ust-abi.h
@@ -168,10 +168,10 @@ struct lttng_ust_calibrate {
 	} u;
 };
 
-#define FILTER_BYTECODE_MAX_LEN		65535
+#define FILTER_BYTECODE_MAX_LEN		65536
 struct lttng_ust_filter_bytecode {
-	uint16_t len;
-	uint16_t reloc_offset;
+	uint32_t len;
+	uint32_t reloc_offset;
 	char data[0];
 };
 
diff --git a/src/bin/lttng-sessiond/main.c b/src/bin/lttng-sessiond/main.c
index 318da74..730ac65 100644
--- a/src/bin/lttng-sessiond/main.c
+++ b/src/bin/lttng-sessiond/main.c
@@ -2659,7 +2659,7 @@ skip_domain:
 	{
 		struct lttng_filter_bytecode *bytecode;
 
-		if (cmd_ctx->lsm->u.filter.bytecode_len > 65336) {
+		if (cmd_ctx->lsm->u.filter.bytecode_len > LTTNG_FILTER_MAX_LEN) {
 			ret = LTTNG_ERR_FILTER_INVAL;
 			goto error;
 		}
diff --git a/src/common/sessiond-comm/sessiond-comm.h b/src/common/sessiond-comm/sessiond-comm.h
index 32ce384..62205f4 100644
--- a/src/common/sessiond-comm/sessiond-comm.h
+++ b/src/common/sessiond-comm/sessiond-comm.h
@@ -208,7 +208,7 @@ struct lttcomm_session_msg {
 	} u;
 };
 
-#define LTTNG_FILTER_MAX_LEN	65336
+#define LTTNG_FILTER_MAX_LEN	65536
 
 /*
  * Filter bytecode data. The reloc table is located at the end of the
@@ -216,8 +216,8 @@ struct lttcomm_session_msg {
  * starts at reloc_table_offset.
  */
 struct lttng_filter_bytecode {
-	uint16_t len;	/* len of data */
-	uint16_t reloc_table_offset;
+	uint32_t len;	/* len of data */
+	uint32_t reloc_table_offset;
 	char data[0];
 };
 
diff --git a/src/lib/lttng-ctl/filter/filter-visitor-generate-bytecode.c b/src/lib/lttng-ctl/filter/filter-visitor-generate-bytecode.c
index 98f8375..332a387 100644
--- a/src/lib/lttng-ctl/filter/filter-visitor-generate-bytecode.c
+++ b/src/lib/lttng-ctl/filter/filter-visitor-generate-bytecode.c
@@ -239,7 +239,7 @@ int visit_node_load(struct filter_parser_ctx *ctx, struct ir_op *node)
 		uint32_t insn_len = sizeof(struct load_op)
 			+ sizeof(struct field_ref);
 		struct field_ref ref_offset;
-		uint16_t reloc_offset;
+		uint32_t reloc_offset;
 
 		insn = calloc(insn_len, 1);
 		if (!insn)
-- 
1.7.11.4