From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Fri, 4 Sep 2015 05:43:31 +0000 (-0400)
Subject: Cleanup: eliminate implicit sign-extension
X-Git-Url: http://git.efficios.com/?p=deliverable%2Flttng-ust.git;a=commitdiff_plain;h=4c5dac0d3db2e2e6daef2f5e137abc2e93ed0302

Cleanup: eliminate implicit sign-extension

Coverity reported:

CID 1321723 (#1 of 1): Unintended sign extension
(SIGN_EXTENSION)sign_extension: Suspicious implicit sign extension:
elf->ehdr->e_shentsize with type unsigned short (16 bits, unsigned) is
promoted in index * elf->ehdr->e_shentsize to type int (32 bits,
signed), then sign-extended to type unsigned long (64 bits, unsigned).
If index * elf->ehdr->e_shentsize is greater than 0x7FFFFFFF, the upper
bits of the result will all be 1.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/liblttng-ust/lttng-ust-elf.c b/liblttng-ust/lttng-ust-elf.c
index dd50f2b6..8d3fc573 100644
--- a/liblttng-ust/lttng-ust-elf.c
+++ b/liblttng-ust/lttng-ust-elf.c
@@ -101,7 +101,7 @@ struct lttng_ust_elf_shdr *lttng_ust_elf_get_shdr(struct lttng_ust_elf *elf,
 						uint16_t index)
 {
 	struct lttng_ust_elf_shdr *shdr = NULL;
-	long offset;
+	off_t offset;
 
 	if (!elf) {
 		goto error;
@@ -116,7 +116,8 @@ struct lttng_ust_elf_shdr *lttng_ust_elf_get_shdr(struct lttng_ust_elf *elf,
 		goto error;
 	}
 
-	offset = elf->ehdr->e_shoff + index * elf->ehdr->e_shentsize;
+	offset = (off_t) elf->ehdr->e_shoff
+		+ (off_t) index * elf->ehdr->e_shentsize;
 	if (lseek(elf->fd, offset, SEEK_SET) < 0) {
 		goto error;
 	}