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dump2tar: fix truncated paths

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When creating a tar archive, dump2tar incorrectly truncates the last
character of file paths that are exactly 100 characters long.

Paths up to 100 characters can be represented in the 100-byte name field
of a tar header entry, while longer paths are handled via an additional
tar data block. For 100-character paths, dump2tar determines that a
single header is sufficient, but then uses util_strlcpy() to store the
path into the name field. Since util_strlcpy() ensures nul-terminated
strings, the final character of the path is overwritten.

Fix this by using strncpy() instead of util_strlcpy(). Also mark the
affected name fields as "nonstring" to prevent associated compiler
warnings.

Reported-by: Steffen Maier <maier@linux.ibm.com>
Fixes: d85cf20981 ("dump2tar: Change SET_STR_FIELD to copy strings correctly")
Reviewed-by: Jan Höppner <hoeppner@linux.ibm.com>
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
This commit is contained in:
Peter Oberparleiter
2023-07-18 13:41:28 +02:00
committed by Jan Höppner
parent d8496160cb
commit 7e53611e3a
1 changed files with 10 additions and 3 deletions
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13
dump2tar/src/tar.c
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@@ -23,9 +23,16 @@
#define BLOCKSIZE 512
#if __has_attribute(nonstring)
# define __nonstring __attribute__ ((nonstring))
#else
# define __nonstring
#endif
/* Basic TAR header */
struct tar_header {
char name[100];
char name[100] __nonstring;
char mode[8];
char uid[8];
char gid[8];
@@ -33,7 +40,7 @@ struct tar_header {
char mtime[12];
char chksum[8];
char typeflag;
char linkname[100];
char linkname[100] __nonstring;
char magic[6];
char version[2];
char uname[32];
@@ -78,7 +85,7 @@ static void set_time(char *dest, size_t len, time_t value)
#define SET_TIME_FIELD(obj, name, value) \
set_time((obj)->name, sizeof((obj)->name), (time_t) (value))
#define SET_STR_FIELD(obj, name, value) \
util_strlcpy((obj)->name, (value), sizeof((obj)->name))
strncpy((obj)->name, (value), sizeof((obj)->name))
/* Initialize the tar file @header with the provided data */
static void init_header(struct tar_header *header, const char *filename,