GHSA-GC4F-HPR3-XWMC
Vulnerability from github – Published: 2025-02-27 21:32 – Updated: 2025-02-27 21:32In 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:
- Open device /dev/tpmrm.
- Remove module tpm_tis_spi.
- 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 [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [] (show_stack) from [] (dump_stack+0xc4/0xd8) [] (dump_stack) from [] (__warn+0x104/0x108) [] (__warn) from [] (warn_slowpath_fmt+0x74/0xb8) [] (warn_slowpath_fmt) from [] (kobject_get+0xa0/0xa4) [] (kobject_get) from [] (tpm_try_get_ops+0x14/0x54 [tpm]) [] (tpm_try_get_ops [tpm]) from [] (tpm_common_write+0x38/0x60 [tpm]) [] (tpm_common_write [tpm]) from [] (vfs_write+0xc4/0x3c0) [] (vfs_write) from [] (ksys_write+0x58/0xcc) [] (ksys_write) from [] (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") 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.
{
"affected": [],
"aliases": [
"CVE-2022-49287"
],
"database_specific": {
"cwe_ids": [
"CWE-416"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-02-26T07:01:05Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\ntpm: fix reference counting for struct tpm_chip\n\nThe following sequence of operations results in a refcount warning:\n\n1. Open device /dev/tpmrm.\n2. Remove module tpm_tis_spi.\n3. Write a TPM command to the file descriptor opened at step 1.\n\n------------[ cut here ]------------\nWARNING: CPU: 3 PID: 1161 at lib/refcount.c:25 kobject_get+0xa0/0xa4\nrefcount_t: addition on 0; use-after-free.\nModules linked in: tpm_tis_spi tpm_tis_core tpm mdio_bcm_unimac brcmfmac\nsha256_generic libsha256 sha256_arm hci_uart btbcm bluetooth cfg80211 vc4\nbrcmutil ecdh_generic ecc snd_soc_core crc32_arm_ce libaes\nraspberrypi_hwmon ac97_bus snd_pcm_dmaengine bcm2711_thermal snd_pcm\nsnd_timer genet snd phy_generic soundcore [last unloaded: spi_bcm2835]\nCPU: 3 PID: 1161 Comm: hold_open Not tainted 5.10.0ls-main-dirty #2\nHardware name: BCM2711\n[\u003cc0410c3c\u003e] (unwind_backtrace) from [\u003cc040b580\u003e] (show_stack+0x10/0x14)\n[\u003cc040b580\u003e] (show_stack) from [\u003cc1092174\u003e] (dump_stack+0xc4/0xd8)\n[\u003cc1092174\u003e] (dump_stack) from [\u003cc0445a30\u003e] (__warn+0x104/0x108)\n[\u003cc0445a30\u003e] (__warn) from [\u003cc0445aa8\u003e] (warn_slowpath_fmt+0x74/0xb8)\n[\u003cc0445aa8\u003e] (warn_slowpath_fmt) from [\u003cc08435d0\u003e] (kobject_get+0xa0/0xa4)\n[\u003cc08435d0\u003e] (kobject_get) from [\u003cbf0a715c\u003e] (tpm_try_get_ops+0x14/0x54 [tpm])\n[\u003cbf0a715c\u003e] (tpm_try_get_ops [tpm]) from [\u003cbf0a7d6c\u003e] (tpm_common_write+0x38/0x60 [tpm])\n[\u003cbf0a7d6c\u003e] (tpm_common_write [tpm]) from [\u003cc05a7ac0\u003e] (vfs_write+0xc4/0x3c0)\n[\u003cc05a7ac0\u003e] (vfs_write) from [\u003cc05a7ee4\u003e] (ksys_write+0x58/0xcc)\n[\u003cc05a7ee4\u003e] (ksys_write) from [\u003cc04001a0\u003e] (ret_fast_syscall+0x0/0x4c)\nException stack(0xc226bfa8 to 0xc226bff0)\nbfa0: 00000000 000105b4 00000003 beafe664 00000014 00000000\nbfc0: 00000000 000105b4 000103f8 00000004 00000000 00000000 b6f9c000 beafe684\nbfe0: 0000006c beafe648 0001056c b6eb6944\n---[ end trace d4b8409def9b8b1f ]---\n\nThe reason for this warning is the attempt to get the chip-\u003edev reference\nin tpm_common_write() although the reference counter is already zero.\n\nSince commit 8979b02aaf1d (\"tpm: Fix reference count to main device\") the\nextra reference used to prevent a premature zero counter is never taken,\nbecause the required TPM_CHIP_FLAG_TPM2 flag is never set.\n\nFix this by moving the TPM 2 character device handling from\ntpm_chip_alloc() to tpm_add_char_device() which is called at a later point\nin time when the flag has been set in case of TPM2.\n\nCommit fdc915f7f719 (\"tpm: expose spaces via a device link /dev/tpmrm\u003cn\u003e\")\nalready introduced function tpm_devs_release() to release the extra\nreference but did not implement the required put on chip-\u003edevs that results\nin the call of this function.\n\nFix this by putting chip-\u003edevs in tpm_chip_unregister().\n\nFinally move the new implementation for the TPM 2 handling into a new\nfunction to avoid multiple checks for the TPM_CHIP_FLAG_TPM2 flag in the\ngood case and error cases.",
"id": "GHSA-gc4f-hpr3-xwmc",
"modified": "2025-02-27T21:32:13Z",
"published": "2025-02-27T21:32:13Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-49287"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/290e05f346d1829e849662c97e42d5ad984f5258"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2f928c0d5c02dbab49e8c19d98725c822f6fc409"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/473a66f99cb8173c14138c5a5c69bfad04e8f9ac"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/662893b4f6bd466ff9e1cd454c44c26d32d554fe"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6e7baf84149fb43950631415de231b3a41915aa3"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7e0438f83dc769465ee663bb5dcf8cc154940712"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a27ed2f3695baf15f9b34d2d7a1f9fc105539a81"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/cb64bd038beacb4331fe464a36c8b5481e8f51e2"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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