From 206ebaea2cd547fbc180d61279bfd2e80a0dc3dd Mon Sep 17 00:00:00 2001 From: Jo-Philipp Wich Date: Wed, 1 Apr 2020 12:41:37 +0200 Subject: [PATCH] file_util.c: fix possible bad memory access in file_read_line_alloc() In the case of a zero length string being returned by fgets(), the condition checking for a trailing new line would perform a bad memory access outside of `buf`. This might happen when line with a leading null byte is read. Avoid this case by checking that the string has a length of at least one byte. Also change the unsigned int types to size_t to store length values while we're at it. Signed-off-by: Jo-Philipp Wich --- libopkg/file_util.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/libopkg/file_util.c b/libopkg/file_util.c index 7e955ed..c0acec3 100644 --- a/libopkg/file_util.c +++ b/libopkg/file_util.c @@ -59,17 +59,14 @@ int file_is_dir(const char *file_name) */ char *file_read_line_alloc(FILE * fp) { + size_t buf_len, line_size; char buf[BUFSIZ]; - unsigned int buf_len; char *line = NULL; - unsigned int line_size = 0; int got_nl = 0; - buf[0] = '\0'; - while (fgets(buf, BUFSIZ, fp)) { buf_len = strlen(buf); - if (buf[buf_len - 1] == '\n') { + if (buf_len > 0 && buf[buf_len - 1] == '\n') { buf_len--; buf[buf_len] = '\0'; got_nl = 1; -- 2.30.2