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Bluetooth: vhci: Avoid needless snprintf() calls

PATCH Applied Kees Cook 6 participants 7 messages Apr 15, 2025

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Kees Cook

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#0 lore raw

PATCH 1/1 Bluetooth: vhci: Avoid needless snprintf() calls

Avoid double-copying of string literals. Use a "const char *" for each string instead of copying from .rodata into stack and then into the skb. We can go directly from .rodata to the skb.

This also works around a Clang bug (that has since been fixed[1]).

---
Cc: Marcel Holtmann <[email protected]>
Cc: Luiz Augusto von Dentz <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: [email protected]

---
 drivers/bluetooth/hci_vhci.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)
drivers/bluetooth/hci_vhci.c +5 -5
index 7651321d351c..9ac22e4a070b 100644
@@ -289,18 +289,18 @@ static void vhci_coredump(struct hci_dev *hdev)
 
 static void vhci_coredump_hdr(struct hci_dev *hdev, struct sk_buff *skb)
 {
-	char buf[80];
+	const char *buf;
 
-	snprintf(buf, sizeof(buf), "Controller Name: vhci_ctrl\n");
+	buf = "Controller Name: vhci_ctrl\n";
 	skb_put_data(skb, buf, strlen(buf));
 
-	snprintf(buf, sizeof(buf), "Firmware Version: vhci_fw\n");
+	buf = "Firmware Version: vhci_fw\n";
 	skb_put_data(skb, buf, strlen(buf));
 
-	snprintf(buf, sizeof(buf), "Driver: vhci_drv\n");
+	buf = "Driver: vhci_drv\n";
 	skb_put_data(skb, buf, strlen(buf));
 
-	snprintf(buf, sizeof(buf), "Vendor: vhci\n");
+	buf = "Vendor: vhci\n";
 	skb_put_data(skb, buf, strlen(buf));
 }
 
Signature · 1 line
2.34.1
Reviewed-by on v1 1/1
#1 lore raw
Quoted 4 lines · Kees Cook

Avoid double-copying of string literals. Use a "const char *" for each string instead of copying from .rodata into stack and then into the skb. We can go directly from .rodata to the skb.

Quoted 8 lines

This also works around a Clang bug (that has since been fixed[1]).

Quoted 42 lines

---
Cc: Marcel Holtmann <[email protected]>
Cc: Luiz Augusto von Dentz <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: [email protected]

---
 drivers/bluetooth/hci_vhci.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)
drivers/bluetooth/hci_vhci.c +5 -5
index 7651321d351c..9ac22e4a070b 100644
@@ -289,18 +289,18 @@ static void vhci_coredump(struct hci_dev *hdev)
 
 static void vhci_coredump_hdr(struct hci_dev *hdev, struct sk_buff *skb)
 {
-	char buf[80];
+	const char *buf;
 
-	snprintf(buf, sizeof(buf), "Controller Name: vhci_ctrl\n");
+	buf = "Controller Name: vhci_ctrl\n";
 	skb_put_data(skb, buf, strlen(buf));
 
-	snprintf(buf, sizeof(buf), "Firmware Version: vhci_fw\n");
+	buf = "Firmware Version: vhci_fw\n";
 	skb_put_data(skb, buf, strlen(buf));
 
-	snprintf(buf, sizeof(buf), "Driver: vhci_drv\n");
+	buf = "Driver: vhci_drv\n";
 	skb_put_data(skb, buf, strlen(buf));
 
-	snprintf(buf, sizeof(buf), "Vendor: vhci\n");
+	buf = "Vendor: vhci\n";
 	skb_put_data(skb, buf, strlen(buf));
 }
 
Signature · 1 line
2.34.1
Reviewed-by on v1 1/1
#2 lore raw
In reply to Kees Cook
Quoted 4 lines · Kees Cook

Avoid double-copying of string literals. Use a "const char *" for each string instead of copying from .rodata into stack and then into the skb. We can go directly from .rodata to the skb.

Quoted 8 lines

This also works around a Clang bug (that has since been fixed[1]).

Thanks!

Signature · 1 line
Josh
#3 lore raw
In reply to Kees Cook

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=953638

---Test result---

Test Summary:

CheckPatch                    PENDING   0.27 seconds
GitLint                       PENDING   0.23 seconds
SubjectPrefix                 PASS      0.13 seconds
BuildKernel                   PASS      24.58 seconds
CheckAllWarning               PASS      26.80 seconds
CheckSparse                   PASS      30.60 seconds
BuildKernel32                 PASS      24.17 seconds
TestRunnerSetup               PASS      463.69 seconds
TestRunner_l2cap-tester       PASS      21.37 seconds
TestRunner_iso-tester         PASS      32.87 seconds
TestRunner_bnep-tester        PASS      4.71 seconds
TestRunner_mgmt-tester        FAIL      120.00 seconds
TestRunner_rfcomm-tester      PASS      7.85 seconds
TestRunner_sco-tester         PASS      12.70 seconds
TestRunner_ioctl-tester       PASS      8.43 seconds
TestRunner_mesh-tester        PASS      6.25 seconds
TestRunner_smp-tester         PASS      7.33 seconds
TestRunner_userchan-tester    PASS      5.06 seconds
IncrementalBuild              PENDING   0.84 seconds

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

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

##############################
Test: TestRunner_mgmt-tester - FAIL
Desc: Run mgmt-tester with test-runner Output:
Total: 490, Passed: 483 (98.6%), Failed: 3, Not Run: 4

Failed Test Cases

LL Privacy - Set Flags 2 (Enable RL)                 Failed       0.147 seconds
LL Privacy - Set Flags 3 (2 Devices to RL)           Failed       0.183 seconds
LL Privacy - Start Discovery 2 (Disable RL)          Failed       0.185 seconds

##############################
Test: IncrementalBuild - PENDING
Desc: Incremental build with the patches in the series Output:

---
Regards,
Linux Bluetooth

#5 lore raw

Hi Kees,

Quoted 8 lines · Kees Cook
Quoted 1 line · On Tue, Apr 15, 2025 at 10:04:09AM -0700, [email protected] wrote:

TestRunner_mgmt-tester FAIL 120.00 seconds

This test looks to be broken? Or the existing tree is broken? It fails with other unrelated patches too, e.g.:

https://patchwork.kernel.org/project/bluetooth/patch/[email protected]/

Probably some false positive, running locally seems to pass so it is most likely something not quite right with github environment.

Quoted 3 lines

--
Kees Cook

Signature · 1 line
Luiz Augusto von Dentz
#6 lore raw
In reply to Kees Cook
This patch was applied to bluetooth/bluetooth-next.git (master) by Luiz Augusto von Dentz <[email protected]>:

Hello:

This patch was applied to bluetooth/bluetooth-next.git (master) by Luiz Augusto von Dentz <[email protected]>:

Quoted 6 lines · On Tue, 15 Apr 2025 09:15:19 -0700 you wrote:

Avoid double-copying of string literals. Use a "const char *" for each string instead of copying from .rodata into stack and then into the skb. We can go directly from .rodata to the skb.

This also works around a Clang bug (that has since been fixed[1]).

Quoted 8 lines

[...]

Here is the summary with links:
- Bluetooth: vhci: Avoid needless snprintf() calls

    https://git.kernel.org/bluetooth/bluetooth-next/c/3b32759328e9

You are awesome, thank you!

Signature · 2 lines
Deet-doot-dot, I am a bot.
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