CVE-2023-52497

En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: erofs: corrige la descompresión in situ de lz4 Actualmente, EROFS puede asignar otro búfer comprimido para la descompresión in situ, que se utilizó para manejar los casos en que algunas páginas de datos comprimidos en realidad no están in situ I/ o. Sin embargo, como la mayoría de los algoritmos LZ77 simples, LZ4 espera que los datos comprimidos estén organizados al final del buffer descomprimido y usa explícitamente memmove() para manejar la superposición: ________________________________________________________ |_ dirección de descompresión --> ____ |_ datos comprimidos _| Aunque EROFS organiza los datos comprimidos de esta manera, normalmente asigna dos buffers virtuales individuales, por lo que el orden relativo es incierto. Anteriormente, apenas se observaba ya que LZ4 solo usa memmove() para literales cortos superpuestos y las implementaciones de memmove x86/arm64 parecen cubrirlo por completo y no tienen este problema. Juhyung informó que se pueden encontrar daños en los datos EROFS en un nuevo procesador Intel x86. Después de algunos análisis, parece que los procesadores x86 recientes con la nueva característica FSRM exponen este problema con "rep movsb". Por ahora, usemos estrictamente el búfer descomprimido para la descompresión in situ de lz4. Más adelante, como mejora útil, podríamos intentar unir estos dos buffers en el orden correcto.

In the Linux kernel, the following vulnerability has been resolved: erofs: fix lz4 inplace decompression Currently EROFS can map another compressed buffer for inplace decompression, that was used to handle the cases that some pages of compressed data are actually not in-place I/O. However, like most simple LZ77 algorithms, LZ4 expects the compressed data is arranged at the end of the decompressed buffer and it explicitly uses memmove() to handle overlapping: __________________________________________________________ |_ direction of decompression --> ____ |_ compressed data _| Although EROFS arranges compressed data like this, it typically maps two individual virtual buffers so the relative order is uncertain. Previously, it was hardly observed since LZ4 only uses memmove() for short overlapped literals and x86/arm64 memmove implementations seem to completely cover it up and they don't have this issue. Juhyung reported that EROFS data corruption can be found on a new Intel x86 processor. After some analysis, it seems that recent x86 processors with the new FSRM feature expose this issue with "rep movsb". Let's strictly use the decompressed buffer for lz4 inplace decompression for now. Later, as an useful improvement, we could try to tie up these two buffers together in the correct order.

Alon Zahavi discovered that the NVMe-oF/TCP subsystem in the Linux kernel did not properly validate H2C PDU data, leading to a null pointer dereference vulnerability. A remote attacker could use this to cause a denial of service. Sander Wiebing, Alvise de Faveri Tron, Herbert Bos, and Cristiano Giuffrida discovered that the Linux kernel mitigations for the initial Branch History Injection vulnerability were insufficient for Intel processors. A local attacker could potentially use this to expose sensitive information.