CVE-2024-24860 bugfix
Gui-Dong Han (1): Bluetooth: Fix atomicity violation in {min,max}_key_size_set
Marcel Holtmann (1): Bluetooth: Move {min,max}_key_size debugfs into hci_debugfs_create_le
net/bluetooth/hci_debugfs.c | 65 ++++++++++++++++++++++++++ net/bluetooth/smp.c | 93 ------------------------------------- 2 files changed, 65 insertions(+), 93 deletions(-)
From: Marcel Holtmann marcel@holtmann.org
mainline inclusion from mainline-v5.6-rc1 commit 18f81241b74fb49d576c83fbbab9a0b6e3bb20d4 category: bugfix bugzilla: 189816 CVE: CVE-2024-24860
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
---------------------------
The debugfs entries for {min,max}_key_size are created during SMP registration and thus it might lead to multiple attempts to create the same entries. Avoid this by moving them to the LE controller init section.
Signed-off-by: Marcel Holtmann marcel@holtmann.org Signed-off-by: Johan Hedberg johan.hedberg@intel.com Signed-off-by: Liu Jian liujian56@huawei.com
Conflicts: net/bluetooth/hci_debugfs.c --- net/bluetooth/hci_debugfs.c | 61 ++++++++++++++++++++++++ net/bluetooth/smp.c | 93 ------------------------------------- 2 files changed, 61 insertions(+), 93 deletions(-)
diff --git a/net/bluetooth/hci_debugfs.c b/net/bluetooth/hci_debugfs.c index 51f5b1efc3a5..16d60376e4e4 100644 --- a/net/bluetooth/hci_debugfs.c +++ b/net/bluetooth/hci_debugfs.c @@ -26,6 +26,7 @@ #include <net/bluetooth/bluetooth.h> #include <net/bluetooth/hci_core.h>
+#include "smp.h" #include "hci_debugfs.h"
#define DEFINE_QUIRK_ATTRIBUTE(__name, __quirk) \ @@ -941,6 +942,62 @@ static int adv_max_interval_get(void *data, u64 *val) DEFINE_SIMPLE_ATTRIBUTE(adv_max_interval_fops, adv_max_interval_get, adv_max_interval_set, "%llu\n");
+static int min_key_size_set(void *data, u64 val) +{ + struct hci_dev *hdev = data; + + if (val > hdev->le_max_key_size || val < SMP_MIN_ENC_KEY_SIZE) + return -EINVAL; + + hci_dev_lock(hdev); + hdev->le_min_key_size = val; + hci_dev_unlock(hdev); + + return 0; +} + +static int min_key_size_get(void *data, u64 *val) +{ + struct hci_dev *hdev = data; + + hci_dev_lock(hdev); + *val = hdev->le_min_key_size; + hci_dev_unlock(hdev); + + return 0; +} + +DEFINE_SIMPLE_ATTRIBUTE(min_key_size_fops, min_key_size_get, + min_key_size_set, "%llu\n"); + +static int max_key_size_set(void *data, u64 val) +{ + struct hci_dev *hdev = data; + + if (val > SMP_MAX_ENC_KEY_SIZE || val < hdev->le_min_key_size) + return -EINVAL; + + hci_dev_lock(hdev); + hdev->le_max_key_size = val; + hci_dev_unlock(hdev); + + return 0; +} + +static int max_key_size_get(void *data, u64 *val) +{ + struct hci_dev *hdev = data; + + hci_dev_lock(hdev); + *val = hdev->le_max_key_size; + hci_dev_unlock(hdev); + + return 0; +} + +DEFINE_SIMPLE_ATTRIBUTE(max_key_size_fops, max_key_size_get, + max_key_size_set, "%llu\n"); + DEFINE_QUIRK_ATTRIBUTE(quirk_strict_duplicate_filter, HCI_QUIRK_STRICT_DUPLICATE_FILTER); DEFINE_QUIRK_ATTRIBUTE(quirk_simultaneous_discovery, @@ -994,6 +1051,10 @@ void hci_debugfs_create_le(struct hci_dev *hdev) &adv_max_interval_fops); debugfs_create_u16("discov_interleaved_timeout", 0644, hdev->debugfs, &hdev->discov_interleaved_timeout); + debugfs_create_file("min_key_size", 0644, hdev->debugfs, hdev, + &min_key_size_fops); + debugfs_create_file("max_key_size", 0644, hdev->debugfs, hdev, + &max_key_size_fops);
debugfs_create_file("quirk_strict_duplicate_filter", 0644, hdev->debugfs, hdev, diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c index 719ae1dff7b4..3935837daab4 100644 --- a/net/bluetooth/smp.c +++ b/net/bluetooth/smp.c @@ -3401,94 +3401,6 @@ static const struct file_operations force_bredr_smp_fops = { .llseek = default_llseek, };
-static ssize_t le_min_key_size_read(struct file *file, - char __user *user_buf, - size_t count, loff_t *ppos) -{ - struct hci_dev *hdev = file->private_data; - char buf[4]; - - snprintf(buf, sizeof(buf), "%2u\n", hdev->le_min_key_size); - - return simple_read_from_buffer(user_buf, count, ppos, buf, strlen(buf)); -} - -static ssize_t le_min_key_size_write(struct file *file, - const char __user *user_buf, - size_t count, loff_t *ppos) -{ - struct hci_dev *hdev = file->private_data; - char buf[32]; - size_t buf_size = min(count, (sizeof(buf) - 1)); - u8 key_size; - - if (copy_from_user(buf, user_buf, buf_size)) - return -EFAULT; - - buf[buf_size] = '\0'; - - sscanf(buf, "%hhu", &key_size); - - if (key_size > hdev->le_max_key_size || - key_size < SMP_MIN_ENC_KEY_SIZE) - return -EINVAL; - - hdev->le_min_key_size = key_size; - - return count; -} - -static const struct file_operations le_min_key_size_fops = { - .open = simple_open, - .read = le_min_key_size_read, - .write = le_min_key_size_write, - .llseek = default_llseek, -}; - -static ssize_t le_max_key_size_read(struct file *file, - char __user *user_buf, - size_t count, loff_t *ppos) -{ - struct hci_dev *hdev = file->private_data; - char buf[4]; - - snprintf(buf, sizeof(buf), "%2u\n", hdev->le_max_key_size); - - return simple_read_from_buffer(user_buf, count, ppos, buf, strlen(buf)); -} - -static ssize_t le_max_key_size_write(struct file *file, - const char __user *user_buf, - size_t count, loff_t *ppos) -{ - struct hci_dev *hdev = file->private_data; - char buf[32]; - size_t buf_size = min(count, (sizeof(buf) - 1)); - u8 key_size; - - if (copy_from_user(buf, user_buf, buf_size)) - return -EFAULT; - - buf[buf_size] = '\0'; - - sscanf(buf, "%hhu", &key_size); - - if (key_size > SMP_MAX_ENC_KEY_SIZE || - key_size < hdev->le_min_key_size) - return -EINVAL; - - hdev->le_max_key_size = key_size; - - return count; -} - -static const struct file_operations le_max_key_size_fops = { - .open = simple_open, - .read = le_max_key_size_read, - .write = le_max_key_size_write, - .llseek = default_llseek, -}; - int smp_register(struct hci_dev *hdev) { struct l2cap_chan *chan; @@ -3513,11 +3425,6 @@ int smp_register(struct hci_dev *hdev)
hdev->smp_data = chan;
- debugfs_create_file("le_min_key_size", 0644, hdev->debugfs, hdev, - &le_min_key_size_fops); - debugfs_create_file("le_max_key_size", 0644, hdev->debugfs, hdev, - &le_max_key_size_fops); - /* If the controller does not support BR/EDR Secure Connections * feature, then the BR/EDR SMP channel shall not be present. *
From: Gui-Dong Han 2045gemini@gmail.com
mainline inclusion from mainline-v6.8-rc1 commit da9065caa594d19b26e1a030fd0cc27bd365d685 category: bugfix bugzilla: 189816 CVE: CVE-2024-24860
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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In min_key_size_set(): if (val > hdev->le_max_key_size || val < SMP_MIN_ENC_KEY_SIZE) return -EINVAL; hci_dev_lock(hdev); hdev->le_min_key_size = val; hci_dev_unlock(hdev);
In max_key_size_set(): if (val > SMP_MAX_ENC_KEY_SIZE || val < hdev->le_min_key_size) return -EINVAL; hci_dev_lock(hdev); hdev->le_max_key_size = val; hci_dev_unlock(hdev);
The atomicity violation occurs due to concurrent execution of set_min and set_max funcs.Consider a scenario where setmin writes a new, valid 'min' value, and concurrently, setmax writes a value that is greater than the old 'min' but smaller than the new 'min'. In this case, setmax might check against the old 'min' value (before acquiring the lock) but write its value after the 'min' has been updated by setmin. This leads to a situation where the 'max' value ends up being smaller than the 'min' value, which is an inconsistency.
This possible bug is found by an experimental static analysis tool developed by our team, BassCheck[1]. This tool analyzes the locking APIs to extract function pairs that can be concurrently executed, and then analyzes the instructions in the paired functions to identify possible concurrency bugs including data races and atomicity violations. The above possible bug is reported when our tool analyzes the source code of Linux 5.17.
To resolve this issue, it is suggested to encompass the validity checks within the locked sections in both set_min and set_max funcs. The modification ensures that the validation of 'val' against the current min/max values is atomic, thus maintaining the integrity of the settings. With this patch applied, our tool no longer reports the bug, with the kernel configuration allyesconfig for x86_64. Due to the lack of associated hardware, we cannot test the patch in runtime testing, and just verify it according to the code logic.
[1] https://sites.google.com/view/basscheck/
Fixes: 18f81241b74f ("Bluetooth: Move {min,max}_key_size debugfs ...") Cc: stable@vger.kernel.org Signed-off-by: Gui-Dong Han 2045gemini@gmail.com Signed-off-by: Luiz Augusto von Dentz luiz.von.dentz@intel.com Signed-off-by: Liu Jian liujian56@huawei.com --- net/bluetooth/hci_debugfs.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/net/bluetooth/hci_debugfs.c b/net/bluetooth/hci_debugfs.c index 16d60376e4e4..18683a76cf25 100644 --- a/net/bluetooth/hci_debugfs.c +++ b/net/bluetooth/hci_debugfs.c @@ -946,10 +946,12 @@ static int min_key_size_set(void *data, u64 val) { struct hci_dev *hdev = data;
- if (val > hdev->le_max_key_size || val < SMP_MIN_ENC_KEY_SIZE) + hci_dev_lock(hdev); + if (val > hdev->le_max_key_size || val < SMP_MIN_ENC_KEY_SIZE) { + hci_dev_unlock(hdev); return -EINVAL; + }
- hci_dev_lock(hdev); hdev->le_min_key_size = val; hci_dev_unlock(hdev);
@@ -974,10 +976,12 @@ static int max_key_size_set(void *data, u64 val) { struct hci_dev *hdev = data;
- if (val > SMP_MAX_ENC_KEY_SIZE || val < hdev->le_min_key_size) + hci_dev_lock(hdev); + if (val > SMP_MAX_ENC_KEY_SIZE || val < hdev->le_min_key_size) { + hci_dev_unlock(hdev); return -EINVAL; + }
- hci_dev_lock(hdev); hdev->le_max_key_size = val; hci_dev_unlock(hdev);
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