Piteball
/
android_kernel_samsung_msm8976
mirror of https://github.com/team-infusion-developers/android_kernel_samsung_msm8976.git
1
1
Fork 0
Code Issues Projects Releases Wiki Activity

staging: android: ashmem: Disallow ashmem memory from being remapped 

When ashmem file is being mmapped the resulting vma->vm_file points to the
backing shmem file with the generic fops that do not check ashmem
permissions like fops of ashmem do. Fix that by disallowing mapping
operation for backing shmem file.

Bug: 142938932
Bug: 142903466
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: I718dfca02c83845f8a41d88506871b0aa21326d7
CVE-2020-0009
Signed-off-by: Kevin F. Haggerty <haggertk@lineageos.org>
This commit is contained in:
Suren Baghdasaryan 2019-10-25 00:12:58 -07:00 committed by L R
parent f5209698f0
commit a90d46376b
1 changed files with 28 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
drivers/staging/android/ashmem.c
View File

@ -290,8 +290,23 @@ static inline vm_flags_t calc_vm_may_flags(unsigned long prot)
_calc_vm_trans(prot, PROT_EXEC, VM_MAYEXEC);
}
static int ashmem_vmfile_mmap(struct file *file, struct vm_area_struct *vma)
{
/* do not allow to mmap ashmem backing shmem file directly */
return -EPERM;
}
static unsigned long
ashmem_vmfile_get_unmapped_area(struct file *file, unsigned long addr,
unsigned long len, unsigned long pgoff,
unsigned long flags)
{
return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
}
static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
{
static struct file_operations vmfile_fops;
struct ashmem_area *asma = file->private_data;
int ret = 0;
@ -331,6 +346,19 @@ static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
goto out;
}
asma->file = vmfile;
/*
* override mmap operation of the vmfile so that it can't be
* remapped which would lead to creation of a new vma with no
* asma permission checks. Have to override get_unmapped_area
* as well to prevent VM_BUG_ON check for f_ops modification.
*/
if (!vmfile_fops.mmap) {
vmfile_fops = *vmfile->f_op;
vmfile_fops.mmap = ashmem_vmfile_mmap;
vmfile_fops.get_unmapped_area =
ashmem_vmfile_get_unmapped_area;
}
vmfile->f_op = &vmfile_fops;
}
get_file(asma->file);