[U-Boot] [PATCH 1/2] FIX: env: import: hashtable: Prevent buffer overrun when importing environment from file

[U-Boot] [PATCH 1/2] FIX: env: import: hashtable: Prevent buffer overrun when importing environment from file

[Lukasz Majewski]

Lets consider following scenario:
- One uses echo -n "key=value" to define environment variable in a file (single variable)
- The file content is "key=value" without any terminating byte (e.g. 0x0a or
0x0d).
- The file is loaded to u-boot non zero'ed RAM buffer (with load command).
- Then "env import -t -r $loadaddr $filesize" is executed.
- Due to lack of proper termination byte we have classical example of buffer
  overrun.

This patch prevents from this by allocating one extra byte than size and
explicitly null terminate it.

There should be no change for normal env import operation after applying
this patch.

Signed-off-by: Lukasz Majewski <l.majewski@majess.pl>
---
 lib/hashtable.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/hashtable.c b/lib/hashtable.c
index 18ed590..7df424a 100644
--- a/lib/hashtable.c
+++ b/lib/hashtable.c
@@ -789,12 +789,13 @@ int himport_r(struct hsearch_data *htab,
 	}
 
 	/* we allocate new space to make sure we can write to the array */
-	if ((data = malloc(size)) == NULL) {
-		debug("himport_r: can't malloc %zu bytes\n", size);
+	if ((data = malloc(size + 1)) == NULL) {
+		debug("himport_r: can't malloc %zu bytes\n", size + 1);
 		__set_errno(ENOMEM);
 		return 0;
 	}
 	memcpy(data, env, size);
+	data[size] = '\0';
 	dp = data;
 
 	/* make a local copy of the list of variables */
-- 
2.1.4

[U-Boot] [PATCH 2/2] FIX: env: import: hashtable: Free memory allocated before exiting from himport_r()

[Lukasz Majewski]

Without this patch memory is not released on early exit.

Signed-off-by: Lukasz Majewski <l.majewski@majess.pl>
---
 lib/hashtable.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/hashtable.c b/lib/hashtable.c
index 7df424a..02b4105 100644
--- a/lib/hashtable.c
+++ b/lib/hashtable.c
@@ -842,8 +842,10 @@ int himport_r(struct hsearch_data *htab,
 		}
 	}
 
-	if(!size)
+	if (!size) {
+		free(data);
 		return 1;		/* everything OK */
+	}
 	if(crlf_is_lf) {
 		/* Remove Carriage Returns in front of Line Feeds */
 		unsigned ignored_crs = 0;
@@ -907,6 +909,7 @@ int himport_r(struct hsearch_data *htab,
 		if (*name == 0) {
 			debug("INSERT: unable to use an empty key\n");
 			__set_errno(EINVAL);
+			free(data);
 			return 0;
 		}
 
-- 
2.1.4

[U-Boot] [U-Boot, 1/2] FIX: env: import: hashtable: Prevent buffer overrun when importing environment from file

[Tom Rini]

On Mon, Sep 14, 2015 at 12:57:03AM +0200, Lukasz Majewski wrote:

> Lets consider following scenario:
> - One uses echo -n "key=value" to define environment variable in a file (single variable)
> - The file content is "key=value" without any terminating byte (e.g. 0x0a or
> 0x0d).
> - The file is loaded to u-boot non zero'ed RAM buffer (with load command).
> - Then "env import -t -r $loadaddr $filesize" is executed.
> - Due to lack of proper termination byte we have classical example of buffer
>   overrun.
> 
> This patch prevents from this by allocating one extra byte than size and
> explicitly null terminate it.
> 
> There should be no change for normal env import operation after applying
> this patch.
> 
> Signed-off-by: Lukasz Majewski <l.majewski@majess.pl>

Applied to u-boot/master, thanks!

-- 
Tom
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[U-Boot] [U-Boot, 2/2] FIX: env: import: hashtable: Free memory allocated before exiting from himport_r()

[Tom Rini]

On Mon, Sep 14, 2015 at 12:57:04AM +0200, Lukasz Majewski wrote:

> Without this patch memory is not released on early exit.
> 
> Signed-off-by: Lukasz Majewski <l.majewski@majess.pl>

Applied to u-boot/master, thanks!

-- 
Tom
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