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authorMathieu Desnoyers <mathieu.desnoyers@efficios.com>2013-02-25 10:20:36 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-03-14 11:29:51 -0700
commit3126603e01babcec7cfe2f284099e2adff095bff (patch)
treeedd0b3fd6d738ef785f4338825b703f1e7fa7db7 /mm
parent96ace773358d2989ea522a1cdccf65d75c1335f3 (diff)
downloadlinux-linaro-stable-3126603e01babcec7cfe2f284099e2adff095bff.tar.gz
Fix: compat_rw_copy_check_uvector() misuse in aio, readv, writev, and security keys
commit 8aec0f5d4137532de14e6554fd5dd201ff3a3c49 upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/process_vm_access.c8
1 files changed, 0 insertions, 8 deletions
diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
index c20ff48994c2..b63e84a7fa88 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;
}