tpm: fix reference counting for struct tpm_chip

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2022-49287
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-02-26 07:01:05 UTC
Updated2026-08-04 10:17:42 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from ADP

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Problem Types: CWE-416 | CWE-416 CWE-416 Use After Free

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7HIGHCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7HIGHCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected fdc915f7f71939ad5a3dda3389b8d2d7a7c5ee66 473a66f99cb8173c14138c5a5c69bfad04e8f9ac git Not specified
CNA Linux Linux affected fdc915f7f71939ad5a3dda3389b8d2d7a7c5ee66 cb64bd038beacb4331fe464a36c8b5481e8f51e2 git Not specified
CNA Linux Linux affected fdc915f7f71939ad5a3dda3389b8d2d7a7c5ee66 a27ed2f3695baf15f9b34d2d7a1f9fc105539a81 git Not specified
CNA Linux Linux affected fdc915f7f71939ad5a3dda3389b8d2d7a7c5ee66 290e05f346d1829e849662c97e42d5ad984f5258 git Not specified
CNA Linux Linux affected fdc915f7f71939ad5a3dda3389b8d2d7a7c5ee66 662893b4f6bd466ff9e1cd454c44c26d32d554fe git Not specified
CNA Linux Linux affected fdc915f7f71939ad5a3dda3389b8d2d7a7c5ee66 2f928c0d5c02dbab49e8c19d98725c822f6fc409 git Not specified
CNA Linux Linux affected fdc915f7f71939ad5a3dda3389b8d2d7a7c5ee66 6e7baf84149fb43950631415de231b3a41915aa3 git Not specified
CNA Linux Linux affected fdc915f7f71939ad5a3dda3389b8d2d7a7c5ee66 7e0438f83dc769465ee663bb5dcf8cc154940712 git Not specified
CNA Linux Linux affected 4.12 Not specified
CNA Linux Linux unaffected 4.12 semver Not specified
CNA Linux Linux unaffected 4.14.276 4.14.* semver Not specified
CNA Linux Linux unaffected 4.19.238 4.19.* semver Not specified
CNA Linux Linux unaffected 5.4.189 5.4.* semver Not specified
CNA Linux Linux unaffected 5.10.110 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.33 5.15.* semver Not specified
CNA Linux Linux unaffected 5.16.19 5.16.* semver Not specified
CNA Linux Linux unaffected 5.17.1 5.17.* semver Not specified
CNA Linux Linux unaffected 5.18 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/6e7baf84149fb43950631415de231b3a41915aa3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/290e05f346d1829e849662c97e42d5ad984f5258 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/7e0438f83dc769465ee663bb5dcf8cc154940712 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/473a66f99cb8173c14138c5a5c69bfad04e8f9ac 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/a27ed2f3695baf15f9b34d2d7a1f9fc105539a81 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/662893b4f6bd466ff9e1cd454c44c26d32d554fe 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/2f928c0d5c02dbab49e8c19d98725c822f6fc409 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/cb64bd038beacb4331fe464a36c8b5481e8f51e2 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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