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authorMathieu Desnoyers <mathieu.desnoyers@efficios.com>2013-02-25 10:20:36 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2013-03-12 11:05:45 -0700
commit8aec0f5d4137532de14e6554fd5dd201ff3a3c49 (patch)
tree314f28e5ad96423c6983aec9270462d76c0bb343 /security
parentc39ac49f23424086b43aceeace243f7a8bcc3ad8 (diff)
downloadlinux-8aec0f5d4137532de14e6554fd5dd201ff3a3c49.tar.gz
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 'security')
-rw-r--r--security/keys/compat.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/security/keys/compat.c b/security/keys/compat.c
index 1c261763f47..d65fa7fa29b 100644
--- a/security/keys/compat.c
+++ b/security/keys/compat.c
@@ -40,12 +40,12 @@ static long compat_keyctl_instantiate_key_iov(
ARRAY_SIZE(iovstack),
iovstack, &iov);
if (ret < 0)
- return ret;
+ goto err;
if (ret == 0)
goto no_payload_free;
ret = keyctl_instantiate_key_common(id, iov, ioc, ret, ringid);
-
+err:
if (iov != iovstack)
kfree(iov);
return ret;