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| author | Greg Kurz <groug@kaod.org> | 2018-11-20 13:00:35 +0100 |
|---|---|---|
| committer | Greg Kurz <groug@kaod.org> | 2018-11-20 13:00:35 +0100 |
| commit | 5b3c77aa581ebb215125c84b0742119483571e55 (patch) | |
| tree | f6d84494a5960a727a2fa90a4350084d24bf98f2 /hw/9pfs | |
| parent | 3c035a41dca808f096a128fe2b62d849fe638a25 (diff) | |
| download | qemu-5b3c77aa581ebb215125c84b0742119483571e55.zip qemu-5b3c77aa581ebb215125c84b0742119483571e55.tar.gz qemu-5b3c77aa581ebb215125c84b0742119483571e55.tar.bz2 | |
9p: take write lock on fid path updates (CVE-2018-19364)
Recent commit 5b76ef50f62079a fixed a race where v9fs_co_open2() could
possibly overwrite a fid path with v9fs_path_copy() while it is being
accessed by some other thread, ie, use-after-free that can be detected
by ASAN with a custom 9p client.
It turns out that the same can happen at several locations where
v9fs_path_copy() is used to set the fid path. The fix is again to
take the write lock.
Fixes CVE-2018-19364.
Cc: P J P <ppandit@redhat.com>
Reported-by: zhibin hu <noirfate@gmail.com>
Reviewed-by: Prasad J Pandit <pjp@fedoraproject.org>
Signed-off-by: Greg Kurz <groug@kaod.org>
Diffstat (limited to 'hw/9pfs')
| -rw-r--r-- | hw/9pfs/9p.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index eef289e..267a255 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -1391,7 +1391,9 @@ static void coroutine_fn v9fs_walk(void *opaque) err = -EINVAL; goto out; } + v9fs_path_write_lock(s); v9fs_path_copy(&fidp->path, &path); + v9fs_path_unlock(s); } else { newfidp = alloc_fid(s, newfid); if (newfidp == NULL) { @@ -2160,6 +2162,7 @@ static void coroutine_fn v9fs_create(void *opaque) V9fsString extension; int iounit; V9fsPDU *pdu = opaque; + V9fsState *s = pdu->s; v9fs_path_init(&path); v9fs_string_init(&name); @@ -2200,7 +2203,9 @@ static void coroutine_fn v9fs_create(void *opaque) if (err < 0) { goto out; } + v9fs_path_write_lock(s); v9fs_path_copy(&fidp->path, &path); + v9fs_path_unlock(s); err = v9fs_co_opendir(pdu, fidp); if (err < 0) { goto out; @@ -2216,7 +2221,9 @@ static void coroutine_fn v9fs_create(void *opaque) if (err < 0) { goto out; } + v9fs_path_write_lock(s); v9fs_path_copy(&fidp->path, &path); + v9fs_path_unlock(s); } else if (perm & P9_STAT_MODE_LINK) { int32_t ofid = atoi(extension.data); V9fsFidState *ofidp = get_fid(pdu, ofid); @@ -2234,7 +2241,9 @@ static void coroutine_fn v9fs_create(void *opaque) fidp->fid_type = P9_FID_NONE; goto out; } + v9fs_path_write_lock(s); v9fs_path_copy(&fidp->path, &path); + v9fs_path_unlock(s); err = v9fs_co_lstat(pdu, &fidp->path, &stbuf); if (err < 0) { fidp->fid_type = P9_FID_NONE; @@ -2272,7 +2281,9 @@ static void coroutine_fn v9fs_create(void *opaque) if (err < 0) { goto out; } + v9fs_path_write_lock(s); v9fs_path_copy(&fidp->path, &path); + v9fs_path_unlock(s); } else if (perm & P9_STAT_MODE_NAMED_PIPE) { err = v9fs_co_mknod(pdu, fidp, &name, fidp->uid, -1, 0, S_IFIFO | (perm & 0777), &stbuf); @@ -2283,7 +2294,9 @@ static void coroutine_fn v9fs_create(void *opaque) if (err < 0) { goto out; } + v9fs_path_write_lock(s); v9fs_path_copy(&fidp->path, &path); + v9fs_path_unlock(s); } else if (perm & P9_STAT_MODE_SOCKET) { err = v9fs_co_mknod(pdu, fidp, &name, fidp->uid, -1, 0, S_IFSOCK | (perm & 0777), &stbuf); @@ -2294,7 +2307,9 @@ static void coroutine_fn v9fs_create(void *opaque) if (err < 0) { goto out; } + v9fs_path_write_lock(s); v9fs_path_copy(&fidp->path, &path); + v9fs_path_unlock(s); } else { err = v9fs_co_open2(pdu, fidp, &name, -1, omode_to_uflags(mode)|O_CREAT, perm, &stbuf); |