Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: vc_screen: fix null-ptr-deref in vcs_notifier() during concurrent vcs_write A KASAN null-ptr-deref was observed in vcs_notifier(): BUG: KASAN: null-ptr-deref in vcs_notifier+0x98/0x130 Read of size 2 at addr qmp_cmd_name: qmp_capabilities, arguments: {} The issue is a race condition in vcs_write(). When the console_lock is temporarily dropped (to copy data from userspace), the vc_data pointer obtained from vcs_vc() may become stale. After re-acquiring the lock, vcs_vc() is called again to re-validate the pointer. If the vc has been deallocated in the meantime, vcs_vc() returns NULL, and the while loop breaks (with written > 0). However, after the loop, vcs_scr_updated(vc) is still called with the now-NULL vc pointer, leading to a null pointer dereference in the notifier chain (vcs_notifier dereferences param->vc). Fix this by adding a NULL check for vc before calling vcs_scr_updated().
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 11dddfbb7a4e62489b01074d6c04d9d1b42e4047 before 43a6281790273c1b0a9ab76609ff0245b968f1e6; affected e3d1adcad5b73c7ed0c7edb35ab68abcaa45cf67 before b6bbb85cf45bf0b070e741997fe0af3a772c5ad5; affected 3338d0b9acde770ee588eead5cac32c25e7048fc before ff4806202749a51938236214adc0281481a57366; affected 8fb9ea65c9d1338b0d2bb0a9122dc942cdd32357 before 8232fca738011ca2ec865b46ec721d1796dc0580; affected 8fb9ea65c9d1338b0d2bb0a9122dc942cdd32357 before 73049768ad57145acd337102c5aa3c788e6642c8; affected 8fb9ea65c9d1338b0d2bb0a9122dc942cdd32357 before 7cc3dd79777f6ae4625ec37e84dd18a26dc88bde; affected 8fb9ea65c9d1338b0d2bb0a9122dc942cdd32357 before 74be188eb2dc1c99d63986167b9a67d415fe7326; affected 8fb9ea65c9d1338b0d2bb0a9122dc942cdd32357 before 09a43e81279b8da15526da09877134b8bcf618b0; affected 8fb9ea65c9d1338b0d2bb0a9122dc942cdd32357 before a287620312dc6dcb9a093417a0e589bf30fcf38a; affected 934de9a9b659785fed3e820bc0c813a460c71fea; affected 0deff678157333d775af190f84696336cdcccd6d; affected a4e3c4c65ae8510e01352c9a4347e05c035b2ce2; affected 1de42e7653d6714a7507ba6696151a1fa028c69f; affected 5.10.181 before 5.10.260; affected 5.15.113 before 5.15.211; affected 6.1.30 before 6.1.177; affected 4.14.327 before 4.15; affected 4.19.284 before 4.20; affected 5.4.244 before 5.5; affected 6.3.4 before 6.4 |
| Linux / Linux | affected 6.4; unaffected 0 before 6.4; unaffected 5.10.260 through 5.10.*; unaffected 5.15.211 through 5.15.*; unaffected 6.1.177 through 6.1.*; unaffected 6.6.144 through 6.6.*; unaffected 6.12.95 through 6.12.*; unaffected 6.18.37 through 6.18.*; unaffected 7.0.14 through 7.0.*; unaffected 7.1.2 through 7.1.*; unaffected 7.2 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/43a6281790273c1b0a9ab76609ff0245b968f1e6
- https://git.kernel.org/stable/c/b6bbb85cf45bf0b070e741997fe0af3a772c5ad5
- https://git.kernel.org/stable/c/ff4806202749a51938236214adc0281481a57366
- https://git.kernel.org/stable/c/8232fca738011ca2ec865b46ec721d1796dc0580
- https://git.kernel.org/stable/c/73049768ad57145acd337102c5aa3c788e6642c8
- https://git.kernel.org/stable/c/7cc3dd79777f6ae4625ec37e84dd18a26dc88bde
- https://git.kernel.org/stable/c/74be188eb2dc1c99d63986167b9a67d415fe7326
- https://git.kernel.org/stable/c/09a43e81279b8da15526da09877134b8bcf618b0
- https://git.kernel.org/stable/c/a287620312dc6dcb9a093417a0e589bf30fcf38a