In the Linux kernel, the following vulnerability has been resolved: tpm: fix reference counting for struct tpm_chip The following sequence of operations results in a refcount warning: 1. Open device /dev/tpmrm. 2. Remove module tpm_tis_spi. 3. Write a TPM command to the file descriptor opened at step 1. ------------[ cut here ]------------ WARNING: CPU: 3 PID: 1161 at lib/refcount.c:25 kobject_get+0xa0/0xa4 refcount_t: addition on 0; use-after-free. Modules linked in: tpm_tis_spi tpm_tis_core tpm mdio_bcm_unimac brcmfmac sha256_generic libsha256 sha256_arm hci_uart btbcm bluetooth cfg80211 vc4 brcmutil ecdh_generic ecc snd_soc_core crc32_arm_ce libaes raspberrypi_hwmon ac97_bus snd_pcm_dmaengine bcm2711_thermal snd_pcm snd_timer genet snd phy_generic soundcore [last unloaded: spi_bcm2835] CPU: 3 PID: 1161 Comm: hold_open Not tainted 5.10.0ls-main-dirty #2 Hardware name: BCM2711 [<c0410c3c>] (unwind_backtrace) from [<c040b580>] (show_stack+0x10/0x14) [<c040b580>] (show_stack) from [<c1092174>] (dump_stack+0xc4/0xd8) [<c1092174>] (dump_stack) from [<c0445a30>] (__warn+0x104/0x108) [<c0445a30>] (__warn) from [<c0445aa8>] (warn_slowpath_fmt+0x74/0xb8) [<c0445aa8>] (warn_slowpath_fmt) from [<c08435d0>] (kobject_get+0xa0/0xa4) [<c08435d0>] (kobject_get) from [<bf0a715c>] (tpm_try_get_ops+0x14/0x54 [tpm]) [<bf0a715c>] (tpm_try_get_ops [tpm]) from [<bf0a7d6c>] (tpm_common_write+0x38/0x60 [tpm]) [<bf0a7d6c>] (tpm_common_write [tpm]) from [<c05a7ac0>] (vfs_write+0xc4/0x3c0) [<c05a7ac0>] (vfs_write) from [<c05a7ee4>] (ksys_write+0x58/0xcc) [<c05a7ee4>] (ksys_write) from [<c04001a0>] (ret_fast_syscall+0x0/0x4c) Exception stack(0xc226bfa8 to 0xc226bff0) bfa0: 00000000 000105b4 00000003 beafe664 00000014 00000000 bfc0: 00000000 000105b4 000103f8 00000004 00000000 00000000 b6f9c000 beafe684 bfe0: 0000006c beafe648 0001056c b6eb6944 ---[ end trace d4b8409def9b8b1f ]--- The reason for this warning is the attempt to get the chip->dev reference in tpm_common_write() although the reference counter is already zero. Since commit 8979b02aaf1d ("tpm: Fix reference count to main device") the extra reference used to prevent a premature zero counter is never taken, because the required TPM_CHIP_FLAG_TPM2 flag is never set. Fix this by moving the TPM 2 character device handling from tpm_chip_alloc() to tpm_add_char_device() which is called at a later point in time when the flag has been set in case of TPM2. Commit fdc915f7f719 ("tpm: expose spaces via a device link /dev/tpmrm<n>") already introduced function tpm_devs_release() to release the extra reference but did not implement the required put on chip->devs that results in the call of this function. Fix this by putting chip->devs in tpm_chip_unregister(). Finally move the new implementation for the TPM 2 handling into a new function to avoid multiple checks for the TPM_CHIP_FLAG_TPM2 flag in the good case and error cases.
This vulnerability carries a HIGH severity rating with a CVSS v3.1 score of 7.8, requiring local system access to exploit with relatively low complexity without requiring user interaction requiring only low-level privileges . The vulnerability impacts confidentiality (data exposure), integrity (unauthorized modifications), and availability (service disruption) for affected systems. Impacting 1 product from linux organizations running these solutions should prioritize assessment and patching.
Reported in 2025, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.
2025-02-26T07:01:05.557
2025-03-25T15:24:24.277
Analyzed
416baaa9-dc9f-4396-8d5f-8c081fb06d67
CVSSv3.1: 7.8 (HIGH)
| Type | Vendor | Product | Version/Range | Vulnerable? |
|---|---|---|---|---|
| Operating System | linux | linux_kernel | < 4.14.276 | Yes |
| Operating System | linux | linux_kernel | < 4.19.238 | Yes |
| Operating System | linux | linux_kernel | < 5.4.189 | Yes |
| Operating System | linux | linux_kernel | < 5.10.110 | Yes |
| Operating System | linux | linux_kernel | < 5.15.33 | Yes |
| Operating System | linux | linux_kernel | < 5.16.19 | Yes |
| Operating System | linux | linux_kernel | < 5.17.1 | Yes |
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