[PATCH] Bluetooth: eir: validate service data length before reading UUID

[PATCH] Bluetooth: eir: validate service data length before reading UUID

[Aamir Ahmed]

eir_get_service_data() reads a 16-bit UUID from the service data using
get_unaligned_le16() without first checking that the data is long enough
to hold a UUID16 (2 bytes). If a malformed EIR entry has a service data
field with only 1 byte of payload (field_len=2), eir_get_data() returns
dlen=1. The subsequent get_unaligned_le16() then reads 1 byte past the
field boundary.

Additionally, if the corrupted UUID happens to match, the length
calculation "dlen - 2" underflows to SIZE_MAX since dlen is size_t.
Current callers either pass NULL for the length parameter or bounds-check
the returned length, but future callers may not.

Add a check that dlen >= sizeof(u16) and skip fields that are too short
to contain a valid UUID16.

Fixes: 8f9ae5b3ae80 ("Bluetooth: eir: Add helpers for managing service data")
Cc: stable@vger.kernel.org
Signed-off-by: Aamir Ahmed <elb12345@hotmail.co.uk>
---
 net/bluetooth/eir.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/net/bluetooth/eir.c b/net/bluetooth/eir.c
index a55696820b22..ee0136bfae40 100644
--- a/net/bluetooth/eir.c
+++ b/net/bluetooth/eir.c
@@ -373,7 +373,15 @@ void *eir_get_service_data(u8 *eir, size_t eir_len, u16 uuid, size_t *len)
 	size_t dlen;
 
 	while ((eir = eir_get_data(eir, eir_len, EIR_SERVICE_DATA, &dlen))) {
-		u16 value = get_unaligned_le16(eir);
+		u16 value;
+
+		if (dlen < sizeof(value)) {
+			eir += dlen;
+			eir_len = eir_end - eir;
+			continue;
+		}
+
+		value = get_unaligned_le16(eir);
 
 		if (uuid == value) {
 			if (len)
-- 
2.43.0

RE: Bluetooth: eir: validate service data length before reading UUID

[bluez.test.bot]

[-- Attachment #1: Type: text/plain, Size: 2470 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=1159232

---Test result---

Test Summary:
CheckPatch                    PASS      0.75 seconds
VerifyFixes                   PASS      0.13 seconds
VerifySignedoff               PASS      0.13 seconds
GitLint                       PASS      0.33 seconds
SubjectPrefix                 PASS      0.13 seconds
BuildKernel                   PASS      28.78 seconds
CheckAllWarning               PASS      31.12 seconds
CheckSparse                   PASS      29.39 seconds
BuildKernel32                 PASS      27.05 seconds
CheckKernelLLVM               SKIP      0.00 seconds
TestRunnerSetup               PASS      511.96 seconds
TestRunner_l2cap-tester       PASS      67.22 seconds
TestRunner_iso-tester         PASS      109.86 seconds
TestRunner_bnep-tester        PASS      20.20 seconds
TestRunner_mgmt-tester        FAIL      228.04 seconds
TestRunner_rfcomm-tester      PASS      27.18 seconds
TestRunner_sco-tester         PASS      33.25 seconds
TestRunner_ioctl-tester       PASS      27.93 seconds
TestRunner_mesh-tester        FAIL      27.37 seconds
TestRunner_smp-tester         PASS      24.28 seconds
TestRunner_userchan-tester    PASS      21.10 seconds
TestRunner_6lowpan-tester     PASS      24.05 seconds
IncrementalBuild              PASS      26.07 seconds

Details
##############################
Test: CheckKernelLLVM - SKIP
Desc: Build kernel with LLVM + context analysis
Output:
Clang not found
##############################
Test: TestRunner_mgmt-tester - FAIL
Desc: Run mgmt-tester with test-runner
Output:
Total: 501, Passed: 495 (98.8%), Failed: 2, Not Run: 4

Failed Test Cases
Read Exp Feature - Success                           Failed       0.260 seconds
LL Privacy - Unpair 1                                Timed out    1.876 seconds
##############################
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    2.588 seconds
Mesh - Send cancel - 2                               Timed out    1.992 seconds


https://github.com/bluez/bluetooth-next/pull/713

---
Regards,
Linux Bluetooth

Re: [PATCH] Bluetooth: eir: validate service data length before reading UUID

[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 Mon,  7 Sep 2026 00:37:43 +0100 you wrote:
> eir_get_service_data() reads a 16-bit UUID from the service data using
> get_unaligned_le16() without first checking that the data is long enough
> to hold a UUID16 (2 bytes). If a malformed EIR entry has a service data
> field with only 1 byte of payload (field_len=2), eir_get_data() returns
> dlen=1. The subsequent get_unaligned_le16() then reads 1 byte past the
> field boundary.
> 
> [...]

Here is the summary with links:
  - Bluetooth: eir: validate service data length before reading UUID
    https://git.kernel.org/bluetooth/bluetooth-next/c/334ddae615d8

You are awesome, thank you!
-- 
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