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* [libnf_ct PATCH v2 1/9] Handle negative snprintf return values properly
@ 2020-06-24 13:29 Daniel Gröber
  2020-06-24 13:29 ` [libnf_ct PATCH v2 2/9] Fix nfexp_snprintf return value docs Daniel Gröber
                   ` (8 more replies)
  0 siblings, 9 replies; 11+ messages in thread
From: Daniel Gröber @ 2020-06-24 13:29 UTC (permalink / raw)
  To: netfilter-devel

Currently the BUFFER_SIZE macro doesn't take negative 'ret' values into
account. A negative return should just be passed through to the caller,
snprintf will already have set 'errno' properly.

Signed-off-by: Daniel Gröber <dxld@darkboxed.org>
---
 include/internal/internal.h | 2 ++
 src/conntrack/api.c         | 6 +++---
 src/conntrack/snprintf.c    | 3 +++
 src/expect/snprintf.c       | 3 +++
 4 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/include/internal/internal.h b/include/internal/internal.h
index bb44e12..b1fc670 100644
--- a/include/internal/internal.h
+++ b/include/internal/internal.h
@@ -41,6 +41,8 @@
 #endif
 
 #define BUFFER_SIZE(ret, size, len, offset)		\
+	if (ret < 0)					\
+		return -1;				\
 	size += ret;					\
 	if (ret > len)					\
 		ret = len;				\
diff --git a/src/conntrack/api.c b/src/conntrack/api.c
index ffa5216..78d7d61 100644
--- a/src/conntrack/api.c
+++ b/src/conntrack/api.c
@@ -1099,9 +1099,9 @@ int nfct_catch(struct nfct_handle *h)
  * print the message just after you receive the destroy event. If you want
  * more accurate timestamping, use NFCT_OF_TIMESTAMP.
  *
- * This function returns the size of the information that _would_ have been 
- * written to the buffer, even if there was no room for it. Thus, the
- * behaviour is similar to snprintf.
+ * On error, -1 is returned and errno is set appropiately. Otherwise the
+ * size of what _would_ be written is returned, even if the size of the
+ * buffer is insufficient. This behaviour is similar to snprintf.
  */
 int nfct_snprintf(char *buf,
 		  unsigned int size,
diff --git a/src/conntrack/snprintf.c b/src/conntrack/snprintf.c
index 17ad885..eb26af4 100644
--- a/src/conntrack/snprintf.c
+++ b/src/conntrack/snprintf.c
@@ -85,6 +85,9 @@ int __snprintf_conntrack(char *buf,
 		return -1;
 	}
 
+	if (size < 0)
+		return size;
+
 	/* NULL terminated string */
 	buf[size+1 > len ? len-1 : size] = '\0';
 
diff --git a/src/expect/snprintf.c b/src/expect/snprintf.c
index 3a104b5..8c2f3e4 100644
--- a/src/expect/snprintf.c
+++ b/src/expect/snprintf.c
@@ -30,6 +30,9 @@ int __snprintf_expect(char *buf,
 		return -1;
 	}
 
+	if (size < 0)
+		return size;
+
 	/* NULL terminated string */
 	buf[size+1 > len ? len-1 : size] = '\0';
 
-- 
2.20.1


^ permalink raw reply related	[flat|nested] 11+ messages in thread
end of thread, other threads:[~2020-07-01 13:46 UTC | newest]

Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-06-24 13:29 [libnf_ct PATCH v2 1/9] Handle negative snprintf return values properly Daniel Gröber
2020-06-24 13:29 ` [libnf_ct PATCH v2 2/9] Fix nfexp_snprintf return value docs Daniel Gröber
2020-06-24 13:29 ` [libnf_ct PATCH v2 3/9] Replace strncpy with snprintf to improve null byte handling Daniel Gröber
2020-06-24 13:30 ` [libnf_ct PATCH v2 4/9] Fix incorrect snprintf size calculation Daniel Gröber
2020-06-24 13:30 ` [libnf_ct PATCH v2 5/9] Add ARRAY_SIZE() macro Daniel Gröber
2020-06-24 13:30 ` [libnf_ct PATCH v2 6/9] Fix buffer overflow on invalid icmp type in setters Daniel Gröber
2020-06-24 13:30 ` [libnf_ct PATCH v2 7/9] Move icmp request>reply type mapping to common file Daniel Gröber
2020-06-24 13:30 ` [libnf_ct PATCH v2 8/9] Fix buffer overflow in protocol related snprintf functions Daniel Gröber
2020-06-24 13:30 ` [libnf_ct PATCH v2 9/9] Fix buffer overflows in __snprintf_protoinfo* like in *2str fns Daniel Gröber
2020-07-01 11:09 ` [libnf_ct PATCH v2 1/9] Handle negative snprintf return values properly Pablo Neira Ayuso
2020-07-01 13:46   ` Daniel Gröber

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