[PATCH] xfs_scrub: fix buffer overflow in string

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* [PATCH] xfs_scrub: fix buffer overflow in string_escape
@ 2025-02-20 22:07 Darrick J. Wong
  2025-02-20 22:10 ` [RFC PATCH] generic/45[34]: add colored emoji variants to unicode tests Darrick J. Wong
                   ` (2 more replies)
  0 siblings, 3 replies; 6+ messages in thread
From: Darrick J. Wong @ 2025-02-20 22:07 UTC (permalink / raw)
  To: Andrey Albershteyn; +Cc: xfs, hch

From: Darrick J. Wong <djwong@kernel.org>

Need to allocate one more byte for the null terminator, just in case the
/entire/ input string consists of non-printable bytes e.g. emoji.

Cc: <linux-xfs@vger.kernel.org> # v4.15.0
Fixes: 396cd0223598bb ("xfs_scrub: warn about suspicious characters in directory/xattr names")
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 scrub/common.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scrub/common.c b/scrub/common.c
index 6eb3c026dc5ac9..7ea0277bc511ce 100644
--- a/scrub/common.c
+++ b/scrub/common.c
@@ -320,7 +320,7 @@ string_escape(
 	char			*q;
 	int			x;
 
-	str = malloc(strlen(in) * 4);
+	str = malloc((strlen(in) * 4) + 1);
 	if (!str)
 		return NULL;
 	for (p = in, q = str; *p != '\0'; p++) {

^ permalink raw reply related	[flat|nested] 6+ messages in thread

* [RFC PATCH] generic/45[34]: add colored emoji variants to unicode tests
  2025-02-20 22:07 [PATCH] xfs_scrub: fix buffer overflow in string_escape Darrick J. Wong
@ 2025-02-20 22:10 ` Darrick J. Wong
  2025-02-24 14:34   ` Christoph Hellwig
  2025-02-24  8:36 ` [PATCH] xfs_scrub: fix buffer overflow in string_escape Andrey Albershteyn
  2025-02-24 14:11 ` Christoph Hellwig
  2 siblings, 1 reply; 6+ messages in thread
From: Darrick J. Wong @ 2025-02-20 22:10 UTC (permalink / raw)
  To: Andrey Albershteyn; +Cc: xfs, hch

From: Darrick J. Wong <djwong@kernel.org>

Ted told me this morning about a recent problem with kernel Unicode name
casefolding vs. emoji -- initially, someone decided that zero-width
joiners should be stripped out of filenames during comparisons, which
lead to malicious git pulls of branches containing "<zwj>.git/config"
files overwriting git repo config files.  A quick fix was to stop
ignoring the "ignorable" code points, but that broke emoji in filenames,
because emoji use zero-width joiners to combine simpler emoji into more
complex ones, or alter skin tones, or colors, etc.  Reportedly the
casefolding code will also fold a red heart into a black one.

So.  To our filename support test, let's add various colors of heart
emoji and various skin tones of heart-hands; and compound emoji
consisting of multiple emoji glued together with zero width joiners.
This actually caused a buffer overflow in the string-escaping functions
of xfs_scrub phase 5 because I hadn't anticipated that we'd end up with
a filename consisting *entirely* of nonprinting bytes.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
 tests/generic/453 |   55 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 tests/generic/454 |   55 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 110 insertions(+)

diff --git a/tests/generic/453 b/tests/generic/453
index 04945ad1085b2d..bd5ce8b2bb11d9 100755
--- a/tests/generic/453
+++ b/tests/generic/453
@@ -203,6 +203,36 @@ setf "job offer.pdf" "actual period"
 setf "llamapirate\xf3\xa0\x80\x81\xf3\xa0\x81\x94\xf3\xa0\x81\xa8\xf3\xa0\x81\xa5\xf3\xa0\x80\xa0\xf3\xa0\x81\xb3\xf3\xa0\x81\xa1\xf3\xa0\x81\xac\xf3\xa0\x81\xa5\xf3\xa0\x81\xb3\xf3\xa0\x80\xa0\xf3\xa0\x81\xa6\xf3\xa0\x81\xaf\xf3\xa0\x81\xb2\xf3\xa0\x80\xa0\xf3\xa0\x81\x93\xf3\xa0\x81\xa5\xf3\xa0\x81\xa1\xf3\xa0\x81\xb4\xf3\xa0\x81\xb4\xf3\xa0\x81\xac\xf3\xa0\x81\xa5\xf3\xa0\x80\xa0\xf3\xa0\x81\xb7\xf3\xa0\x81\xa5\xf3\xa0\x81\xb2\xf3\xa0\x81\xa5\xf3\xa0\x80\xa0\xf3\xa0\x81\x95\xf3\xa0\x81\x93\xf3\xa0\x81\x84\xf3\xa0\x80\xa0\xf3\xa0\x80\xb1\xf3\xa0\x80\xb2\xf3\xa0\x80\xb0\xf3\xa0\x80\xb0\xf3\xa0\x80\xb0\xf3\xa0\x80\xb0\xf3\xa0\x81\xbf"
 setf "llamapirate"
 
+# colored heart emoji to check if casefolding whacks emoji
+setf "\xf0\x9f\x92\x9c" "purple"
+setf "\xf0\x9f\x92\x99" "blue"
+setf "\xf0\x9f\x92\x9a" "green"
+setf "\xf0\x9f\x92\x9b" "yellow"
+setf "\xf0\x9f\xab\x80" "heart"
+setf "\xe2\x9d\xa4\xef\xb8\x8f" "red"
+setf "\xf0\x9f\xa4\x8e" "brown"
+setf "\xf0\x9f\xa4\x8d" "white"
+setf "\xf0\x9f\x96\xa4" "black"
+setf "\xf0\x9f\xa7\xa1" "orange"
+setf "\xe2\x99\xa5\xef\xb8\x8f" "red suit"
+
+# zero width joiners exist in the middle of emoji sequences aren't supposed
+# to be normalized to nothing, but apparently this caused issues with
+# casefolding on ext4; also the mending heart caused a crash in xfs_scrub
+setf "\xf0\x9f\x92\x94" "broken heart"
+setf "\xe2\x9d\xa4\xef\xb8\x8f\xe2\x80\x8d\xf0\x9f\xa9\xb9" "mending heart"
+setf "\xf0\x9f\xa7\x91\xf0\x9f\x8f\xbb\xe2\x80\x8d\xe2\x9d\xa4\xef\xb8
+\x8f\xe2\x80\x8d\xf0\x9f\xa7\x91\xf0\x9f\x8f\xbc" "couple with heart"
+setf "\xf0\x9f\xa7\x91\xf0\x9f\x8f\xbb\xe2\x80\x8d\xe2\x9d\xa4\xef\xb8\x8f\xe2\x80\x8d\xf0\x9f\xa7\x91\xf0\x9f\x8f\xbf" "couple with heart, light and dark skin tone"
+
+# emoji heart hands with skin tone variations
+setf "\xf0\x9f\xab\xb6\xf0\x9f\x8f\xbf" "dark"
+setf "\xf0\x9f\xab\xb6\xf0\x9f\x8f\xbe" "medium dark"
+setf "\xf0\x9f\xab\xb6\xf0\x9f\x8f\xbd" "medium"
+setf "\xf0\x9f\xab\xb6\xf0\x9f\x8f\xbc" "medium light"
+setf "\xf0\x9f\xab\xb6\xf0\x9f\x8f\xbb" "light"
+setf "\xf0\x9f\xab\xb6" "neutral"
+
 ls -laR $testdir >> $seqres.full
 
 echo "Test files"
@@ -276,6 +306,31 @@ testf "job offer.pdf" "actual period"
 testf "llamapirate\xf3\xa0\x80\x81\xf3\xa0\x81\x94\xf3\xa0\x81\xa8\xf3\xa0\x81\xa5\xf3\xa0\x80\xa0\xf3\xa0\x81\xb3\xf3\xa0\x81\xa1\xf3\xa0\x81\xac\xf3\xa0\x81\xa5\xf3\xa0\x81\xb3\xf3\xa0\x80\xa0\xf3\xa0\x81\xa6\xf3\xa0\x81\xaf\xf3\xa0\x81\xb2\xf3\xa0\x80\xa0\xf3\xa0\x81\x93\xf3\xa0\x81\xa5\xf3\xa0\x81\xa1\xf3\xa0\x81\xb4\xf3\xa0\x81\xb4\xf3\xa0\x81\xac\xf3\xa0\x81\xa5\xf3\xa0\x80\xa0\xf3\xa0\x81\xb7\xf3\xa0\x81\xa5\xf3\xa0\x81\xb2\xf3\xa0\x81\xa5\xf3\xa0\x80\xa0\xf3\xa0\x81\x95\xf3\xa0\x81\x93\xf3\xa0\x81\x84\xf3\xa0\x80\xa0\xf3\xa0\x80\xb1\xf3\xa0\x80\xb2\xf3\xa0\x80\xb0\xf3\xa0\x80\xb0\xf3\xa0\x80\xb0\xf3\xa0\x80\xb0\xf3\xa0\x81\xbf"
 testf "llamapirate"
 
+testf "\xf0\x9f\x92\x9c" "purple"
+testf "\xf0\x9f\x92\x99" "blue"
+testf "\xf0\x9f\x92\x9a" "green"
+testf "\xf0\x9f\x92\x9b" "yellow"
+testf "\xf0\x9f\xab\x80" "heart"
+testf "\xe2\x9d\xa4\xef\xb8\x8f" "red"
+testf "\xf0\x9f\xa4\x8e" "brown"
+testf "\xf0\x9f\xa4\x8d" "white"
+testf "\xf0\x9f\x96\xa4" "black"
+testf "\xf0\x9f\xa7\xa1" "orange"
+testf "\xe2\x99\xa5\xef\xb8\x8f" "red suit"
+
+testf "\xf0\x9f\x92\x94" "broken heart"
+testf "\xe2\x9d\xa4\xef\xb8\x8f\xe2\x80\x8d\xf0\x9f\xa9\xb9" "mending heart"
+testf "\xf0\x9f\xa7\x91\xf0\x9f\x8f\xbb\xe2\x80\x8d\xe2\x9d\xa4\xef\xb8
+\x8f\xe2\x80\x8d\xf0\x9f\xa7\x91\xf0\x9f\x8f\xbc" "couple with heart"
+testf "\xf0\x9f\xa7\x91\xf0\x9f\x8f\xbb\xe2\x80\x8d\xe2\x9d\xa4\xef\xb8\x8f\xe2\x80\x8d\xf0\x9f\xa7\x91\xf0\x9f\x8f\xbf" "couple with heart, light and dark skin tone"
+
+testf "\xf0\x9f\xab\xb6\xf0\x9f\x8f\xbf" "dark"
+testf "\xf0\x9f\xab\xb6\xf0\x9f\x8f\xbe" "medium dark"
+testf "\xf0\x9f\xab\xb6\xf0\x9f\x8f\xbd" "medium"
+testf "\xf0\x9f\xab\xb6\xf0\x9f\x8f\xbc" "medium light"
+testf "\xf0\x9f\xab\xb6\xf0\x9f\x8f\xbb" "light"
+testf "\xf0\x9f\xab\xb6" "neutral"
+
 echo "Uniqueness of inodes?"
 stat -c '%i' "${testdir}/"* | sort | uniq -c | while read nr inum; do
 	if [ "${nr}" -gt 1 ]; then
diff --git a/tests/generic/454 b/tests/generic/454
index aec8beb8b43ca0..9f6ddb4a0e48b2 100755
--- a/tests/generic/454
+++ b/tests/generic/454
@@ -124,6 +124,36 @@ setf "combmark_\xe1\x80\x9c\xe1\x80\xaf\xe1\x80\xad.txt" "combining marks"
 setf "llamapirate\xf3\xa0\x80\x81\xf3\xa0\x81\x94\xf3\xa0\x81\xa8\xf3\xa0\x81\xa5\xf3\xa0\x80\xa0\xf3\xa0\x81\xb3\xf3\xa0\x81\xa1\xf3\xa0\x81\xac\xf3\xa0\x81\xa5\xf3\xa0\x81\xb3\xf3\xa0\x80\xa0\xf3\xa0\x81\xa6\xf3\xa0\x81\xaf\xf3\xa0\x81\xb2\xf3\xa0\x80\xa0\xf3\xa0\x81\x93\xf3\xa0\x81\xa5\xf3\xa0\x81\xa1\xf3\xa0\x81\xb4\xf3\xa0\x81\xb4\xf3\xa0\x81\xac\xf3\xa0\x81\xa5\xf3\xa0\x80\xa0\xf3\xa0\x81\xb7\xf3\xa0\x81\xa5\xf3\xa0\x81\xb2\xf3\xa0\x81\xa5\xf3\xa0\x80\xa0\xf3\xa0\x81\x95\xf3\xa0\x81\x93\xf3\xa0\x81\x84\xf3\xa0\x80\xa0\xf3\xa0\x80\xb1\xf3\xa0\x80\xb2\xf3\xa0\x80\xb0\xf3\xa0\x80\xb0\xf3\xa0\x80\xb0\xf3\xa0\x80\xb0\xf3\xa0\x81\xbf" "secret instructions"
 setf "llamapirate" "no secret instructions"
 
+# colored heart emoji to check if casefolding whacks emoji
+setf "\xf0\x9f\x92\x9c" "purple"
+setf "\xf0\x9f\x92\x99" "blue"
+setf "\xf0\x9f\x92\x9a" "green"
+setf "\xf0\x9f\x92\x9b" "yellow"
+setf "\xf0\x9f\xab\x80" "heart"
+setf "\xe2\x9d\xa4\xef\xb8\x8f" "red"
+setf "\xf0\x9f\xa4\x8e" "brown"
+setf "\xf0\x9f\xa4\x8d" "white"
+setf "\xf0\x9f\x96\xa4" "black"
+setf "\xf0\x9f\xa7\xa1" "orange"
+setf "\xe2\x99\xa5\xef\xb8\x8f" "red suit"
+
+# zero width joiners exist in the middle of emoji sequences aren't supposed
+# to be normalized to nothing, but apparently this caused issues with
+# casefolding on ext4; also the mending heart caused a crash in xfs_scrub
+setf "\xf0\x9f\x92\x94" "broken heart"
+setf "\xe2\x9d\xa4\xef\xb8\x8f\xe2\x80\x8d\xf0\x9f\xa9\xb9" "mending heart"
+setf "\xf0\x9f\xa7\x91\xf0\x9f\x8f\xbb\xe2\x80\x8d\xe2\x9d\xa4\xef\xb8
+\x8f\xe2\x80\x8d\xf0\x9f\xa7\x91\xf0\x9f\x8f\xbc" "couple with heart"
+setf "\xf0\x9f\xa7\x91\xf0\x9f\x8f\xbb\xe2\x80\x8d\xe2\x9d\xa4\xef\xb8\x8f\xe2\x80\x8d\xf0\x9f\xa7\x91\xf0\x9f\x8f\xbf" "couple with heart, light and dark skin tone"
+
+# emoji heart hands with skin tone variations
+setf "\xf0\x9f\xab\xb6\xf0\x9f\x8f\xbf" "dark"
+setf "\xf0\x9f\xab\xb6\xf0\x9f\x8f\xbe" "medium dark"
+setf "\xf0\x9f\xab\xb6\xf0\x9f\x8f\xbd" "medium"
+setf "\xf0\x9f\xab\xb6\xf0\x9f\x8f\xbc" "medium light"
+setf "\xf0\x9f\xab\xb6\xf0\x9f\x8f\xbb" "light"
+setf "\xf0\x9f\xab\xb6" "neutral"
+
 _getfattr --absolute-names -d "${testfile}" >> $seqres.full
 
 echo "Test files"
@@ -174,6 +204,31 @@ testf "combmark_\xe1\x80\x9c\xe1\x80\xaf\xe1\x80\xad.txt" "combining marks"
 testf "llamapirate\xf3\xa0\x80\x81\xf3\xa0\x81\x94\xf3\xa0\x81\xa8\xf3\xa0\x81\xa5\xf3\xa0\x80\xa0\xf3\xa0\x81\xb3\xf3\xa0\x81\xa1\xf3\xa0\x81\xac\xf3\xa0\x81\xa5\xf3\xa0\x81\xb3\xf3\xa0\x80\xa0\xf3\xa0\x81\xa6\xf3\xa0\x81\xaf\xf3\xa0\x81\xb2\xf3\xa0\x80\xa0\xf3\xa0\x81\x93\xf3\xa0\x81\xa5\xf3\xa0\x81\xa1\xf3\xa0\x81\xb4\xf3\xa0\x81\xb4\xf3\xa0\x81\xac\xf3\xa0\x81\xa5\xf3\xa0\x80\xa0\xf3\xa0\x81\xb7\xf3\xa0\x81\xa5\xf3\xa0\x81\xb2\xf3\xa0\x81\xa5\xf3\xa0\x80\xa0\xf3\xa0\x81\x95\xf3\xa0\x81\x93\xf3\xa0\x81\x84\xf3\xa0\x80\xa0\xf3\xa0\x80\xb1\xf3\xa0\x80\xb2\xf3\xa0\x80\xb0\xf3\xa0\x80\xb0\xf3\xa0\x80\xb0\xf3\xa0\x80\xb0\xf3\xa0\x81\xbf" "secret instructions"
 testf "llamapirate" "no secret instructions"
 
+testf "\xf0\x9f\x92\x9c" "purple"
+testf "\xf0\x9f\x92\x99" "blue"
+testf "\xf0\x9f\x92\x9a" "green"
+testf "\xf0\x9f\x92\x9b" "yellow"
+testf "\xf0\x9f\xab\x80" "heart"
+testf "\xe2\x9d\xa4\xef\xb8\x8f" "red"
+testf "\xf0\x9f\xa4\x8e" "brown"
+testf "\xf0\x9f\xa4\x8d" "white"
+testf "\xf0\x9f\x96\xa4" "black"
+testf "\xf0\x9f\xa7\xa1" "orange"
+testf "\xe2\x99\xa5\xef\xb8\x8f" "red suit"
+
+testf "\xf0\x9f\x92\x94" "broken heart"
+testf "\xe2\x9d\xa4\xef\xb8\x8f\xe2\x80\x8d\xf0\x9f\xa9\xb9" "mending heart"
+testf "\xf0\x9f\xa7\x91\xf0\x9f\x8f\xbb\xe2\x80\x8d\xe2\x9d\xa4\xef\xb8
+\x8f\xe2\x80\x8d\xf0\x9f\xa7\x91\xf0\x9f\x8f\xbc" "couple with heart"
+testf "\xf0\x9f\xa7\x91\xf0\x9f\x8f\xbb\xe2\x80\x8d\xe2\x9d\xa4\xef\xb8\x8f\xe2\x80\x8d\xf0\x9f\xa7\x91\xf0\x9f\x8f\xbf" "couple with heart, light and dark skin tone"
+
+testf "\xf0\x9f\xab\xb6\xf0\x9f\x8f\xbf" "dark"
+testf "\xf0\x9f\xab\xb6\xf0\x9f\x8f\xbe" "medium dark"
+testf "\xf0\x9f\xab\xb6\xf0\x9f\x8f\xbd" "medium"
+testf "\xf0\x9f\xab\xb6\xf0\x9f\x8f\xbc" "medium light"
+testf "\xf0\x9f\xab\xb6\xf0\x9f\x8f\xbb" "light"
+testf "\xf0\x9f\xab\xb6" "neutral"
+
 echo "Uniqueness of keys?"
 crazy_keys="$(_getfattr --absolute-names -d "${testfile}" | grep -E -c '(french_|chinese_|greek_|arabic_|urk)')"
 expected_keys=11

^ permalink raw reply related	[flat|nested] 6+ messages in thread

* Re: [RFC PATCH] generic/45[34]: add colored emoji variants to unicode tests
  2025-02-20 22:10 ` [RFC PATCH] generic/45[34]: add colored emoji variants to unicode tests Darrick J. Wong
@ 2025-02-24 14:34   ` Christoph Hellwig
  0 siblings, 0 replies; 6+ messages in thread
From: Christoph Hellwig @ 2025-02-24 14:34 UTC (permalink / raw)
  To: Darrick J. Wong; +Cc: Andrey Albershteyn, xfs

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] xfs_scrub: fix buffer overflow in string_escape
  2025-02-20 22:07 [PATCH] xfs_scrub: fix buffer overflow in string_escape Darrick J. Wong
  2025-02-20 22:10 ` [RFC PATCH] generic/45[34]: add colored emoji variants to unicode tests Darrick J. Wong
@ 2025-02-24  8:36 ` Andrey Albershteyn
  2025-02-24 14:11 ` Christoph Hellwig
  2 siblings, 0 replies; 6+ messages in thread
From: Andrey Albershteyn @ 2025-02-24  8:36 UTC (permalink / raw)
  To: Darrick J. Wong; +Cc: xfs, hch

On 2025-02-20 14:07:58, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
> 
> Need to allocate one more byte for the null terminator, just in case the
> /entire/ input string consists of non-printable bytes e.g. emoji.
> 
> Cc: <linux-xfs@vger.kernel.org> # v4.15.0
> Fixes: 396cd0223598bb ("xfs_scrub: warn about suspicious characters in directory/xattr names")
> Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> ---
>  scrub/common.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/scrub/common.c b/scrub/common.c
> index 6eb3c026dc5ac9..7ea0277bc511ce 100644
> --- a/scrub/common.c
> +++ b/scrub/common.c
> @@ -320,7 +320,7 @@ string_escape(
>  	char			*q;
>  	int			x;
>  
> -	str = malloc(strlen(in) * 4);
> +	str = malloc((strlen(in) * 4) + 1);
>  	if (!str)
>  		return NULL;
>  	for (p = in, q = str; *p != '\0'; p++) {
> 

Looks good to me
Reviewed-by: Andrey Albershteyn <aalbersh@kernel.org>

-- 
- Andrey


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] xfs_scrub: fix buffer overflow in string_escape
  2025-02-20 22:07 [PATCH] xfs_scrub: fix buffer overflow in string_escape Darrick J. Wong
  2025-02-20 22:10 ` [RFC PATCH] generic/45[34]: add colored emoji variants to unicode tests Darrick J. Wong
  2025-02-24  8:36 ` [PATCH] xfs_scrub: fix buffer overflow in string_escape Andrey Albershteyn
@ 2025-02-24 14:11 ` Christoph Hellwig
  2025-02-24 17:54   ` Darrick J. Wong
  2 siblings, 1 reply; 6+ messages in thread
From: Christoph Hellwig @ 2025-02-24 14:11 UTC (permalink / raw)
  To: Darrick J. Wong; +Cc: Andrey Albershteyn, xfs

On Thu, Feb 20, 2025 at 02:07:58PM -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
> 
> Need to allocate one more byte for the null terminator, just in case the
> /entire/ input string consists of non-printable bytes e.g. emoji.
> 
> Cc: <linux-xfs@vger.kernel.org> # v4.15.0
> Fixes: 396cd0223598bb ("xfs_scrub: warn about suspicious characters in directory/xattr names")
> Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> ---
>  scrub/common.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/scrub/common.c b/scrub/common.c
> index 6eb3c026dc5ac9..7ea0277bc511ce 100644
> --- a/scrub/common.c
> +++ b/scrub/common.c
> @@ -320,7 +320,7 @@ string_escape(
>  	char			*q;
>  	int			x;
>  
> -	str = malloc(strlen(in) * 4);
> +	str = malloc((strlen(in) * 4) + 1);

Nit: no need for the inner braces.

But this open code string allocation and manipulation makes me feel
really bad.  Assuming we don't have a good alternative, can you
at least throw in a comment explaining the allocation length here?


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] xfs_scrub: fix buffer overflow in string_escape
  2025-02-24 14:11 ` Christoph Hellwig
@ 2025-02-24 17:54   ` Darrick J. Wong
  0 siblings, 0 replies; 6+ messages in thread
From: Darrick J. Wong @ 2025-02-24 17:54 UTC (permalink / raw)
  To: Christoph Hellwig; +Cc: Andrey Albershteyn, xfs

On Mon, Feb 24, 2025 at 03:11:03PM +0100, Christoph Hellwig wrote:
> On Thu, Feb 20, 2025 at 02:07:58PM -0800, Darrick J. Wong wrote:
> > From: Darrick J. Wong <djwong@kernel.org>
> > 
> > Need to allocate one more byte for the null terminator, just in case the
> > /entire/ input string consists of non-printable bytes e.g. emoji.
> > 
> > Cc: <linux-xfs@vger.kernel.org> # v4.15.0
> > Fixes: 396cd0223598bb ("xfs_scrub: warn about suspicious characters in directory/xattr names")
> > Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> > ---
> >  scrub/common.c |    2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/scrub/common.c b/scrub/common.c
> > index 6eb3c026dc5ac9..7ea0277bc511ce 100644
> > --- a/scrub/common.c
> > +++ b/scrub/common.c
> > @@ -320,7 +320,7 @@ string_escape(
> >  	char			*q;
> >  	int			x;
> >  
> > -	str = malloc(strlen(in) * 4);
> > +	str = malloc((strlen(in) * 4) + 1);
> 
> Nit: no need for the inner braces.
> 
> But this open code string allocation and manipulation makes me feel
> really bad.  Assuming we don't have a good alternative, can you
> at least throw in a comment explaining the allocation length here?

Ok.  I'll change the code to read as follows:

	/*
	 * Each non-printing byte renders as a four-byte escape sequence, so
	 * allocate 4x the input length, plus a byte for the null terminator.
	 */
	str = malloc(strlen(in) * 4 + 1);

--D

^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2025-02-24 17:54 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-02-20 22:07 [PATCH] xfs_scrub: fix buffer overflow in string_escape Darrick J. Wong
2025-02-20 22:10 ` [RFC PATCH] generic/45[34]: add colored emoji variants to unicode tests Darrick J. Wong
2025-02-24 14:34   ` Christoph Hellwig
2025-02-24  8:36 ` [PATCH] xfs_scrub: fix buffer overflow in string_escape Andrey Albershteyn
2025-02-24 14:11 ` Christoph Hellwig
2025-02-24 17:54   ` Darrick J. Wong

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