* Re: [PATCH] fs/ntfs3: return -ERANGE for short xattr buffers
2026-07-09 7:18 [PATCH] fs/ntfs3: return -ERANGE for short xattr buffers Baolin Liu
@ 2026-07-09 7:27 ` liubaolin
2026-09-28 17:22 ` Konstantin Komarov
1 sibling, 0 replies; 3+ messages in thread
From: liubaolin @ 2026-07-09 7:27 UTC (permalink / raw)
To: almaz.alexandrovich; +Cc: ntfs3, linux-kernel, liubaolin12138, Baolin Liu
Dear maintainer,
I found an issue where `ntfs3` returns the wrong errno when reading
`system.ntfs_attrib` with a buffer that is too small.
When the user buffer is too small, `ntfs3` currently returns `-ENODATA`.
However, `system.ntfs_attrib` does exist in this case, and the failure
is only caused by the user buffer being too small.
A more appropriate return value here is `-ERANGE`, not `-ENODATA`, which
normally indicates that the xattr does not exist.
To reproduce this issue, I wrote a simple test program,
`ntfs3_xattr_smallbuf.c`.
First, build the test program:
gcc -O2 -Wall -o ntfs3_xattr_smallbuf ntfs3_xattr_smallbuf.c
Then reproduce it with the following steps:
truncate -s 128M /tmp/ntfs3.img
mkntfs -F -q /tmp/ntfs3.img
mkdir -p /tmp/ntfs3-mnt
mount -o loop -t ntfs3 /tmp/ntfs3.img /tmp/ntfs3-mnt
touch /tmp/ntfs3-mnt/testfile
./ntfs3_xattr_smallbuf /tmp/ntfs3-mnt/testfile
On the unpatched kernel, I see the following result:
$ ./ntfs3_xattr_smallbuf /tmp/ntfs3-mnt/testfile
getxattr failed: errno=61 (No data available)
`system.ntfs_attrib` does exist, but when the buffer is too
small it returns `ENODATA`.
With this patch applied, the same test gives:
$ ./ntfs3_xattr_smallbuf /tmp/ntfs3-mnt/testfile
getxattr failed: errno=34 (Numerical result out of range)
In this case, it returns `ERANGE`.
Best regards,
Baolin
***********************************************************************************************
ntfs3_xattr_smallbuf.c:
#define _GNU_SOURCE
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <sys/xattr.h>
int main(int argc, char *argv[])
{
const char *path = argc > 1 ? argv[1] : "/tmp/ntfs3-mnt/testfile";
char buf[1];
ssize_t ret;
ret = getxattr(path, "system.ntfs_attrib", buf, sizeof(buf));
if (ret < 0) {
printf("getxattr failed: errno=%d (%s)\n", errno,
strerror(errno));
return 1;
}
printf("getxattr succeeded: ret=%zd\n", ret);
return 0;
}
**********************************************************************************************
在 2026/7/9 15:18, Baolin Liu 写道:
> From: Baolin Liu <liubaolin@kylinos.cn>
>
> ntfs3 currently returns -ENODATA when the xattr exists
> but the user buffer is too small.
> Return -ERANGE instead.
>
> Signed-off-by: Baolin Liu <liubaolin@kylinos.cn>
> ---
> fs/ntfs3/xattr.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/fs/ntfs3/xattr.c b/fs/ntfs3/xattr.c
> index 9743a63a152e..0a19668e970d 100644
> --- a/fs/ntfs3/xattr.c
> +++ b/fs/ntfs3/xattr.c
> @@ -781,7 +781,7 @@ static int ntfs_getxattr(const struct xattr_handler *handler, struct dentry *de,
> if (!buffer) {
> err = sizeof(u8);
> } else if (size < sizeof(u8)) {
> - err = -ENODATA;
> + err = -ERANGE;
> } else {
> err = sizeof(u8);
> *(u8 *)buffer = le32_to_cpu(ni->std_fa);
> @@ -795,7 +795,7 @@ static int ntfs_getxattr(const struct xattr_handler *handler, struct dentry *de,
> if (!buffer) {
> err = sizeof(u32);
> } else if (size < sizeof(u32)) {
> - err = -ENODATA;
> + err = -ERANGE;
> } else {
> err = sizeof(u32);
> *(u32 *)buffer = le32_to_cpu(ni->std_fa);
> @@ -835,7 +835,7 @@ static int ntfs_getxattr(const struct xattr_handler *handler, struct dentry *de,
> if (!buffer) {
> err = sd_size;
> } else if (size < sd_size) {
> - err = -ENODATA;
> + err = -ERANGE;
> } else {
> err = sd_size;
> memcpy(buffer, sd, sd_size);
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] fs/ntfs3: return -ERANGE for short xattr buffers
2026-07-09 7:18 [PATCH] fs/ntfs3: return -ERANGE for short xattr buffers Baolin Liu
2026-07-09 7:27 ` liubaolin
@ 2026-09-28 17:22 ` Konstantin Komarov
1 sibling, 0 replies; 3+ messages in thread
From: Konstantin Komarov @ 2026-09-28 17:22 UTC (permalink / raw)
To: Baolin Liu; +Cc: ntfs3, linux-kernel, liubaolin12138, Baolin Liu
On 7/9/26 09:18, Baolin Liu wrote:
> From: Baolin Liu <liubaolin@kylinos.cn>
>
> ntfs3 currently returns -ENODATA when the xattr exists
> but the user buffer is too small.
> Return -ERANGE instead.
>
> Signed-off-by: Baolin Liu <liubaolin@kylinos.cn>
> ---
> fs/ntfs3/xattr.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/fs/ntfs3/xattr.c b/fs/ntfs3/xattr.c
> index 9743a63a152e..0a19668e970d 100644
> --- a/fs/ntfs3/xattr.c
> +++ b/fs/ntfs3/xattr.c
> @@ -781,7 +781,7 @@ static int ntfs_getxattr(const struct xattr_handler *handler, struct dentry *de,
> if (!buffer) {
> err = sizeof(u8);
> } else if (size < sizeof(u8)) {
> - err = -ENODATA;
> + err = -ERANGE;
> } else {
> err = sizeof(u8);
> *(u8 *)buffer = le32_to_cpu(ni->std_fa);
> @@ -795,7 +795,7 @@ static int ntfs_getxattr(const struct xattr_handler *handler, struct dentry *de,
> if (!buffer) {
> err = sizeof(u32);
> } else if (size < sizeof(u32)) {
> - err = -ENODATA;
> + err = -ERANGE;
> } else {
> err = sizeof(u32);
> *(u32 *)buffer = le32_to_cpu(ni->std_fa);
> @@ -835,7 +835,7 @@ static int ntfs_getxattr(const struct xattr_handler *handler, struct dentry *de,
> if (!buffer) {
> err = sd_size;
> } else if (size < sd_size) {
> - err = -ENODATA;
> + err = -ERANGE;
> } else {
> err = sd_size;
> memcpy(buffer, sd, sd_size);
Hello,
Your patch was applied, thank you.
Regards,
Konstantin
^ permalink raw reply [flat|nested] 3+ messages in thread