[PATCH] Bluetooth: vhci: Avoid needless snprintf() calls

[PATCH] Bluetooth: vhci: Avoid needless snprintf() calls

[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.

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

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202401250927.1poZERd6-lkp@intel.com/
Fixes: ab4e4380d4e1 ("Bluetooth: Add vhci devcoredump support")
Link: https://github.com/llvm/llvm-project/commit/ea2e66aa8b6e363b89df66dc44275a0d7ecd70ce [1]
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
---
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-bluetooth@vger.kernel.org
---
 drivers/bluetooth/hci_vhci.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/bluetooth/hci_vhci.c b/drivers/bluetooth/hci_vhci.c
index 7651321d351c..9ac22e4a070b 100644
--- a/drivers/bluetooth/hci_vhci.c
+++ b/drivers/bluetooth/hci_vhci.c
@@ -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));
 }
 
-- 
2.34.1

Re: [PATCH] Bluetooth: vhci: Avoid needless snprintf() calls

[Nathan Chancellor]

On Tue, Apr 15, 2025 at 09:15:19AM -0700, Kees Cook 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]).
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202401250927.1poZERd6-lkp@intel.com/
> Fixes: ab4e4380d4e1 ("Bluetooth: Add vhci devcoredump support")
> Link: https://github.com/llvm/llvm-project/commit/ea2e66aa8b6e363b89df66dc44275a0d7ecd70ce [1]
> Cc: stable@vger.kernel.org
> Signed-off-by: Kees Cook <kees@kernel.org>

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

> ---
> Cc: Marcel Holtmann <marcel@holtmann.org>
> Cc: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
> Cc: Josh Poimboeuf <jpoimboe@kernel.org>
> Cc: Nathan Chancellor <nathan@kernel.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: linux-bluetooth@vger.kernel.org
> ---
>  drivers/bluetooth/hci_vhci.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/bluetooth/hci_vhci.c b/drivers/bluetooth/hci_vhci.c
> index 7651321d351c..9ac22e4a070b 100644
> --- a/drivers/bluetooth/hci_vhci.c
> +++ b/drivers/bluetooth/hci_vhci.c
> @@ -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));
>  }
>  
> -- 
> 2.34.1
> 

Re: [PATCH] Bluetooth: vhci: Avoid needless snprintf() calls

[Josh Poimboeuf]

On Tue, Apr 15, 2025 at 09:15:19AM -0700, Kees Cook 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]).
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202401250927.1poZERd6-lkp@intel.com/
> Fixes: ab4e4380d4e1 ("Bluetooth: Add vhci devcoredump support")
> Link: https://github.com/llvm/llvm-project/commit/ea2e66aa8b6e363b89df66dc44275a0d7ecd70ce [1]
> Cc: stable@vger.kernel.org
> Signed-off-by: Kees Cook <kees@kernel.org>

Thanks!

Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>

-- 
Josh

RE: Bluetooth: vhci: Avoid needless snprintf() calls

[bluez.test.bot]

[-- Attachment #1: Type: text/plain, Size: 2109 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=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

Re: Bluetooth: vhci: Avoid needless snprintf() calls

[Kees Cook]

On Tue, Apr 15, 2025 at 10:04:09AM -0700, bluez.test.bot@gmail.com 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/20250411165608.871089-2-luiz.dentz@gmail.com/

-- 
Kees Cook

Re: Bluetooth: vhci: Avoid needless snprintf() calls

[Luiz Augusto von Dentz]

Hi Kees,

On Tue, Apr 15, 2025 at 1:16 PM Kees Cook <kees@kernel.org> wrote:
>
> On Tue, Apr 15, 2025 at 10:04:09AM -0700, bluez.test.bot@gmail.com 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/20250411165608.871089-2-luiz.dentz@gmail.com/

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

> --
> Kees Cook
>


-- 
Luiz Augusto von Dentz

Re: [PATCH] Bluetooth: vhci: Avoid needless snprintf() calls

[patchwork-bot+bluetooth]

Hello:

This patch was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <luiz.von.dentz@intel.com>:

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]).
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202401250927.1poZERd6-lkp@intel.com/
> Fixes: ab4e4380d4e1 ("Bluetooth: Add vhci devcoredump support")
> Link: https://github.com/llvm/llvm-project/commit/ea2e66aa8b6e363b89df66dc44275a0d7ecd70ce [1]
> Cc: stable@vger.kernel.org
> Signed-off-by: Kees Cook <kees@kernel.org>
> 
> [...]

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!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html