Vigil@nce: Linux kernel, memory reading via XFS FSGEOMETRY_V1
February 2011 by Vigil@nce
This bulletin was written by Vigil@nce : http://vigilance.fr/
SYNTHESIS OF THE VULNERABILITY
An attacker can use FSGEOMETRY_V1 ioctls on a XFS filesystem, in order to obtain four bytes from the kernel memory.
Creation date: 16/02/2011
DESCRIPTION OF THE VULNERABILITY
The XFS_IOC_FSGEOMETRY_V1 and XFS_IOC_FSGEOMETRY_V1_32 ioctls return information about the geometry of a XFS filesystem.
These ioctls call the xfs_fs_geometry() function. However, this function does not initialize the logsunit field (integer of 32 bit) of the xfs_fsop_geom_t structure. This structure is then returned to the user.
An attacker can therefore use FSGEOMETRY_V1 ioctls on a XFS filesystem, in order to obtain four bytes from the kernel memory.
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