"file" can be already freed if bprm->file is NULL after
search_binary_handler() return. binfmt_script will do exactly that for
example. If the VM reuses the file after fput run(), this will result in
a use ater free.
So obtain d_is_su before search_binary_handler() runs.
This should explain this crash:
[25333.009554] Unable to handle kernel NULL pointer dereference at virtual address 00000185
[..]
[25333.009918] [2: am:21861] PC is at do_execve+0x354/0x474
Change-Id: I2a8a814d1c0aa75625be83cb30432cf13f1a0681
Signed-off-by: Kevin F. Haggerty <haggertk@lineageos.org>
* 3.10 doesn't normally use iterate for filesystems,
but it was backported in hopes of removing vfs_readdir()
* Because the romnt variable was only set for filesystems
using iterate, the su hide patches were broken for many
filesytems like ext4, which still use vfs_readdir()
instead of iterate_dir() like their mainline counterparts
* Remove the iterate check around setting romnt to fix this
Change-Id: I26426683df0fd199a80f053294f352e31754bec5
It has been claimed that the PG implementation of 'su' has security
vulnerabilities even when disabled. Unfortunately, the people that
find these vulnerabilities often like to keep them private so they
can profit from exploits while leaving users exposed to malicious
hackers.
In order to reduce the attack surface for vulnerabilites, it is
therefore necessary to make 'su' completely inaccessible when it
is not in use (except by the root and system users).
Change-Id: I79716c72f74d0b7af34ec3a8054896c6559a181d
New method - ->iterate(file, ctx). That's the replacement for ->readdir();
it takes callback from ctx->actor, uses ctx->pos instead of file->f_pos and
calls dir_emit(ctx, ...) instead of filldir(data, ...). It does *not*
update file->f_pos (or look at it, for that matter); iterate_dir() does the
update.
Note that dir_emit() takes the offset from ctx->pos (and eventually
filldir_t will lose that argument).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
iterate_dir(): new helper, replacing vfs_readdir().
struct dir_context: contains the readdir callback (and will get more stuff
in it), embedded into whatever data that callback wants to deal with;
eventually, we'll be passing it to ->readdir() replacement instead of
(data,filldir) pair.
Change-Id: Idb3843e77b97d52490b297b1f9e7d7efab18eaef
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Andrea Arcangeli