[oe-commits] [openembedded-core] branch master-next updated: qemu: Limit paths searched during user mode emulation

[git at git.openembedded.org]

rpurdie pushed a commit to branch master-next
in repository openembedded-core.

The following commit(s) were added to refs/heads/master-next by this push:
       new  40f591e   qemu: Limit paths searched during user mode emulation
40f591e is described below

commit 40f591ea1a638fa5b6c23a87539d4f16fd1751e5
Author: Richard Purdie <richard.purdie at linuxfoundation.org>
AuthorDate: Wed Mar 9 22:49:02 2016 +0000

    qemu: Limit paths searched during user mode emulation
    
    By default qemu builds a complete list of directories within the user
    emulation sysroot (-L option). The OE sysroot directory is large and
    this is confusing, for example it indexes all pkgdata. In particular this
    confuses strace of qemu binaries with tons of irrelevant paths.
    
    This patch stops the code indexing up front and instead only indexes
    things if/as/when it needs to. This drastically reduces the files it
    reads and reduces memory usage and cleans up strace.
    
    It would also avoid the infinite directory traversal bug in [YOCTO #6996]
    although the code could still be vulnerable if it parsed those specific
    paths.
    
    Signed-off-by: Richard Purdie <richard.purdie at linuxfoundation.org>
---
 meta/recipes-devtools/qemu/qemu/pathlimit.patch | 90 +++++++++++++++++++++++++
 meta/recipes-devtools/qemu/qemu_2.5.0.bb        |  1 +
 2 files changed, 91 insertions(+)

diff --git a/meta/recipes-devtools/qemu/qemu/pathlimit.patch b/meta/recipes-devtools/qemu/qemu/pathlimit.patch
new file mode 100644
index 0000000..c0ca8ac
--- /dev/null
+++ b/meta/recipes-devtools/qemu/qemu/pathlimit.patch
@@ -0,0 +1,90 @@
+By default qemu builds a complete list of directories within the user
+emulation sysroot (-L option). The OE sysroot directory is large and
+this is confusing, for example it indexes all pkgdata. In particular this
+confuses strace of qemu binaries with tons of irrelevant paths.
+
+This patch stops the code indexing up front and instead only indexes
+things if/as/when it needs to. This drastically reduces the files it
+reads and reduces memory usage and cleans up strace.
+
+It would also avoid the infinite directory traversal bug in [YOCTO #6996]
+although the code could still be vulnerable if it parsed those specific 
+paths.
+
+RP
+2016/3/9
+Upstream-Status: Pending
+
+Index: qemu-2.5.0/util/path.c
+===================================================================
+--- qemu-2.5.0.orig/util/path.c
++++ qemu-2.5.0/util/path.c
+@@ -19,6 +19,7 @@ struct pathelem
+     char *name;
+     /* Full path name, eg. /usr/gnemul/x86-linux/lib. */
+     char *pathname;
++    int populated_entries;
+     struct pathelem *parent;
+     /* Children */
+     unsigned int num_entries;
+@@ -49,6 +50,7 @@ static struct pathelem *new_entry(const
+     new->name = g_strdup(name);
+     new->pathname = g_strdup_printf("%s/%s", root, name);
+     new->num_entries = 0;
++    new->populated_entries = 0;
+     return new;
+ }
+ 
+@@ -57,11 +59,11 @@ static struct pathelem *new_entry(const
+ /* Not all systems provide this feature */
+ #if defined(DT_DIR) && defined(DT_UNKNOWN) && defined(DT_LNK)
+ # define dirent_type(dirent) ((dirent)->d_type)
+-# define is_dir_maybe(type) \
+-    ((type) == DT_DIR || (type) == DT_UNKNOWN || (type) == DT_LNK)
++# define is_not_dir(type) \
++    ((type) != DT_DIR && (type) != DT_UNKNOWN && (type) != DT_LNK)
+ #else
+ # define dirent_type(dirent) (1)
+-# define is_dir_maybe(type)  (type)
++# define is_not_dir(type)  (0)
+ #endif
+ 
+ static struct pathelem *add_dir_maybe(struct pathelem *path)
+@@ -78,6 +80,7 @@ static struct pathelem *add_dir_maybe(st
+         }
+         closedir(dir);
+     }
++    path->populated_entries = 1;
+     return path;
+ }
+ 
+@@ -93,8 +96,8 @@ static struct pathelem *add_entry(struct
+     e = &root->entries[root->num_entries-1];
+ 
+     *e = new_entry(root->pathname, root, name);
+-    if (is_dir_maybe(type)) {
+-        *e = add_dir_maybe(*e);
++    if (is_not_dir(type)) {
++        (*e)->populated_entries = 1;
+     }
+ 
+     return root;
+@@ -112,7 +115,7 @@ static void set_parents(struct pathelem
+ 
+ /* FIXME: Doesn't handle DIR/.. where DIR is not in emulated dir. */
+ static const char *
+-follow_path(const struct pathelem *cursor, const char *name)
++follow_path(struct pathelem *cursor, const char *name)
+ {
+     unsigned int i, namelen;
+ 
+@@ -128,6 +131,9 @@ follow_path(const struct pathelem *curso
+     if (strneq(name, namelen, "."))
+         return follow_path(cursor, name + namelen);
+ 
++    if (!cursor->populated_entries)
++        cursor = add_dir_maybe(cursor);
++
+     for (i = 0; i < cursor->num_entries; i++)
+         if (strneq(name, namelen, cursor->entries[i]->name))
+             return follow_path(cursor->entries[i], name + namelen);
diff --git a/meta/recipes-devtools/qemu/qemu_2.5.0.bb b/meta/recipes-devtools/qemu/qemu_2.5.0.bb
index 4398a18..e9d9a8d 100644
--- a/meta/recipes-devtools/qemu/qemu_2.5.0.bb
+++ b/meta/recipes-devtools/qemu/qemu_2.5.0.bb
@@ -10,6 +10,7 @@ SRC_URI += "file://configure-fix-Darwin-target-detection.patch \
             file://CVE-2016-1568.patch \
             file://CVE-2016-2197.patch \
             file://CVE-2016-2198.patch \
+            file://pathlimit.patch \
            "
 SRC_URI_prepend = "http://wiki.qemu-project.org/download/${BP}.tar.bz2"
 SRC_URI[md5sum] = "f469f2330bbe76e3e39db10e9ac4f8db"

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