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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 | |
parent | c39ac49f23424086b43aceeace243f7a8bcc3ad8 (diff) | |
download | linux-3.10-8aec0f5d4137532de14e6554fd5dd201ff3a3c49.tar.gz linux-3.10-8aec0f5d4137532de14e6554fd5dd201ff3a3c49.tar.bz2 linux-3.10-8aec0f5d4137532de14e6554fd5dd201ff3a3c49.zip |
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>
-rw-r--r-- | fs/compat.c | 15 | ||||
-rw-r--r-- | mm/process_vm_access.c | 8 | ||||
-rw-r--r-- | security/keys/compat.c | 4 |
3 files changed, 9 insertions, 18 deletions
diff --git a/fs/compat.c b/fs/compat.c index fe40fde2911..d487985dd0e 100644 --- a/fs/compat.c +++ b/fs/compat.c @@ -558,6 +558,10 @@ ssize_t compat_rw_copy_check_uvector(int type, } *ret_pointer = iov; + ret = -EFAULT; + if (!access_ok(VERIFY_READ, uvector, nr_segs*sizeof(*uvector))) + goto out; + /* * Single unix specification: * We should -EINVAL if an element length is not >= 0 and fitting an @@ -1080,17 +1084,12 @@ static ssize_t compat_do_readv_writev(int type, struct file *file, if (!file->f_op) goto out; - ret = -EFAULT; - if (!access_ok(VERIFY_READ, uvector, nr_segs*sizeof(*uvector))) - goto out; - - tot_len = compat_rw_copy_check_uvector(type, uvector, nr_segs, + ret = compat_rw_copy_check_uvector(type, uvector, nr_segs, UIO_FASTIOV, iovstack, &iov); - if (tot_len == 0) { - ret = 0; + if (ret <= 0) goto out; - } + tot_len = ret; ret = rw_verify_area(type, file, pos, tot_len); if (ret < 0) goto out; 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; } 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; |