Grub2: jfs: integer overflow when handling symlinks may lead to heap based out-of-bounds write when reading data

A flaw was found in grub2. When reading data from a jfs filesystem, grub's jfs filesystem module uses user-controlled parameters from the filesystem geometry to determine the internal buffer size, however, it improperly checks for integer overflows. A maliciouly crafted filesystem may lead some of those buffer size calculations to overflow, causing it to perform a grub_malloc() operation with a smaller size than expected. As a result, the grub_jfs_lookup_symlink() function will write past the internal buffer length during grub_jfs_read_file(). This issue can be leveraged to corrupt grub's internal critical data and may result in arbitrary code execution, by-passing secure boot protections.

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

跨界内存写

GNU GRUB 缓冲区错误漏洞

GNU GRUB是GNU社区的一款Linux系统引导程序。 GNU GRUB存在缓冲区错误漏洞，该漏洞源于jfs模块包含一个处理符号链接时发生整数溢出问题，导致读取数据时发生基于堆的越界写入。

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