[PATCH v2 net-next] net: 6lowpan: replace sprintf() with scnprintf() in debugfs

[PATCH v2 net-next] net: 6lowpan: replace sprintf() with scnprintf() in debugfs

[Kathara Sasikumar]

sprintf() does not perform bounds checking on the destination buffer.
Replace it with scnprintf() to ensure the write stays within bounds.

No functional change intended.

Signed-off-by: Kathara Sasikumar <katharasasikumar007@gmail.com>
---
v2:
 - Updated commit message wording
 - Targeted the patch to net-next
---
 net/6lowpan/debugfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/6lowpan/debugfs.c b/net/6lowpan/debugfs.c
index 600b9563bfc5..d45ace484143 100644
--- a/net/6lowpan/debugfs.c
+++ b/net/6lowpan/debugfs.c
@@ -173,7 +173,7 @@ static void lowpan_dev_debugfs_ctx_init(struct net_device *dev,
 	if (WARN_ON_ONCE(id >= LOWPAN_IPHC_CTX_TABLE_SIZE))
 		return;
 
-	sprintf(buf, "%d", id);
+	scnprintf(buf, sizeof(buf), "%d", id);
 
 	root = debugfs_create_dir(buf, ctx);
 
-- 
2.51.0

RE: [v2,net-next] net: 6lowpan: replace sprintf() with scnprintf() in debugfs

[bluez.test.bot]

[-- Attachment #1: Type: text/plain, Size: 3080 bytes --]

This is automated email and please do not reply to this email!

Dear submitter,

Thank you for submitting the patches to the linux bluetooth mailing list.
This is a CI test results with your patch series:
PW Link:https://patchwork.kernel.org/project/bluetooth/list/?series=1039078

---Test result---

Test Summary:
CheckPatch                    PENDING   0.32 seconds
GitLint                       PENDING   0.28 seconds
SubjectPrefix                 FAIL      0.49 seconds
BuildKernel                   PASS      25.75 seconds
CheckAllWarning               PASS      28.09 seconds
CheckSparse                   PASS      31.65 seconds
BuildKernel32                 PASS      24.79 seconds
TestRunnerSetup               PASS      545.07 seconds
TestRunner_l2cap-tester       PASS      27.89 seconds
TestRunner_iso-tester         FAIL      48.79 seconds
TestRunner_bnep-tester        PASS      6.08 seconds
TestRunner_mgmt-tester        FAIL      112.60 seconds
TestRunner_rfcomm-tester      PASS      9.31 seconds
TestRunner_sco-tester         FAIL      14.22 seconds
TestRunner_ioctl-tester       PASS      10.02 seconds
TestRunner_mesh-tester        FAIL      11.45 seconds
TestRunner_smp-tester         PASS      8.48 seconds
TestRunner_userchan-tester    PASS      6.42 seconds
IncrementalBuild              PENDING   0.74 seconds

Details
##############################
Test: CheckPatch - PENDING
Desc: Run checkpatch.pl script
Output:

##############################
Test: GitLint - PENDING
Desc: Run gitlint
Output:

##############################
Test: SubjectPrefix - FAIL
Desc: Check subject contains "Bluetooth" prefix
Output:
"Bluetooth: " prefix is not specified in the subject
##############################
Test: TestRunner_iso-tester - FAIL
Desc: Run iso-tester with test-runner
Output:
BUG: KASAN: slab-use-after-free in iso_conn_hold_unless_zero+0x76/0x1c0
Total: 141, Passed: 141 (100.0%), Failed: 0, Not Run: 0
##############################
Test: TestRunner_mgmt-tester - FAIL
Desc: Run mgmt-tester with test-runner
Output:
Total: 494, Passed: 488 (98.8%), Failed: 2, Not Run: 4

Failed Test Cases
Read Exp Feature - Success                           Failed       0.103 seconds
LL Privacy - Set Flags 2 (Enable RL)                 Failed       0.166 seconds
##############################
Test: TestRunner_sco-tester - FAIL
Desc: Run sco-tester with test-runner
Output:
WARNING: possible circular locking dependency detected
BUG: sleeping function called from invalid context at net/core/sock.c:3782
Total: 30, Passed: 30 (100.0%), Failed: 0, Not Run: 0
##############################
Test: TestRunner_mesh-tester - FAIL
Desc: Run mesh-tester with test-runner
Output:
Total: 10, Passed: 8 (80.0%), Failed: 2, Not Run: 0

Failed Test Cases
Mesh - Send cancel - 1                               Timed out    1.994 seconds
Mesh - Send cancel - 2                               Timed out    1.992 seconds
##############################
Test: IncrementalBuild - PENDING
Desc: Incremental build with the patches in the series
Output:



---
Regards,
Linux Bluetooth

Re: [PATCH v2 net-next] net: 6lowpan: replace sprintf() with scnprintf() in debugfs

[Jakub Kicinski]

On Tue,  6 Jan 2026 17:16:11 +0000 Kathara Sasikumar wrote:
> sprintf() does not perform bounds checking on the destination buffer.
> Replace it with scnprintf() to ensure the write stays within bounds.

Aren't compilers clever enough these days to warn about potential
overflows? AFAICT the buffer is 32B so it will definitely fit %d
no matter what.
-- 
pw-bot: reject

Re: [PATCH v2 net-next] net: 6lowpan: replace sprintf() with scnprintf() in debugfs

[Simon Horman]

On Tue, Jan 06, 2026 at 05:16:11PM +0000, Kathara Sasikumar wrote:
> sprintf() does not perform bounds checking on the destination buffer.
> Replace it with scnprintf() to ensure the write stays within bounds.
> 
> No functional change intended.
> 
> Signed-off-by: Kathara Sasikumar <katharasasikumar007@gmail.com>
> ---
> v2:
>  - Updated commit message wording
>  - Targeted the patch to net-next

Thanks for the updates.