diff options
author | Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | 2013-02-25 10:20:36 -0500 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-03-12 11:05:45 -0700 |
commit | 8aec0f5d4137532de14e6554fd5dd201ff3a3c49 (patch) | |
tree | 314f28e5ad96423c6983aec9270462d76c0bb343 /mm/process_vm_access.c | |
parent | c39ac49f23424086b43aceeace243f7a8bcc3ad8 (diff) |
Fix: compat_rw_copy_check_uvector() misuse in aio, readv, writev, and security keys
Looking at mm/process_vm_access.c:process_vm_rw() and comparing it to
compat_process_vm_rw() shows that the compatibility code requires an
explicit "access_ok()" check before calling
compat_rw_copy_check_uvector(). The same difference seems to appear when
we compare fs/read_write.c:do_readv_writev() to
fs/compat.c:compat_do_readv_writev().
This subtle difference between the compat and non-compat requirements
should probably be debated, as it seems to be error-prone. In fact,
there are two others sites that use this function in the Linux kernel,
and they both seem to get it wrong:
Now shifting our attention to fs/aio.c, we see that aio_setup_iocb()
also ends up calling compat_rw_copy_check_uvector() through
aio_setup_vectored_rw(). Unfortunately, the access_ok() check appears to
be missing. Same situation for
security/keys/compat.c:compat_keyctl_instantiate_key_iov().
I propose that we add the access_ok() check directly into
compat_rw_copy_check_uvector(), so callers don't have to worry about it,
and it therefore makes the compat call code similar to its non-compat
counterpart. Place the access_ok() check in the same location where
copy_from_user() can trigger a -EFAULT error in the non-compat code, so
the ABI behaviors are alike on both compat and non-compat.
While we are here, fix compat_do_readv_writev() so it checks for
compat_rw_copy_check_uvector() negative return values.
And also, fix a memory leak in compat_keyctl_instantiate_key_iov() error
handling.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/process_vm_access.c')
-rw-r--r-- | mm/process_vm_access.c | 8 |
1 files changed, 0 insertions, 8 deletions
diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c index 926b4664974..fd26d043350 100644 --- a/mm/process_vm_access.c +++ b/mm/process_vm_access.c @@ -429,12 +429,6 @@ compat_process_vm_rw(compat_pid_t pid, if (flags != 0) return -EINVAL; - if (!access_ok(VERIFY_READ, lvec, liovcnt * sizeof(*lvec))) - goto out; - - if (!access_ok(VERIFY_READ, rvec, riovcnt * sizeof(*rvec))) - goto out; - if (vm_write) rc = compat_rw_copy_check_uvector(WRITE, lvec, liovcnt, UIO_FASTIOV, iovstack_l, @@ -459,8 +453,6 @@ free_iovecs: kfree(iov_r); if (iov_l != iovstack_l) kfree(iov_l); - -out: return rc; } |