From: Stefan Hajnoczi <stefa...@redhat.com> The following pattern is unsafe:
char buf[32]; ret = read(fd, buf, sizeof(buf)); ... buf[ret] = 0; If read(2) returns 32 then a byte beyond the end of the buffer is zeroed. In practice this buffer overflow does not occur because the sysfs max_segments file only contains an unsigned short + '\n'. The string is always shorter than 32 bytes. Regardless, avoid this pattern because static analysis tools might complain and it could lead to real buffer overflows if copy-pasted elsewhere in the codebase. Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com> Signed-off-by: Kevin Wolf <kw...@redhat.com> --- block/file-posix.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/file-posix.c b/block/file-posix.c index c4c0663..ac6bd9f 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -686,7 +686,7 @@ static int hdev_get_max_segments(const struct stat *st) goto out; } do { - ret = read(fd, buf, sizeof(buf)); + ret = read(fd, buf, sizeof(buf) - 1); } while (ret == -1 && errno == EINTR); if (ret < 0) { ret = -errno; -- 1.8.3.1