In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
fbdev: vfb: defer cleanup until the last reference<\/p>\n
FBIOGETCMAP takes a shallow snapshot of info->cmap and performs the
\nusercopy after dropping info->lock. vfb_remove() frees the colormap
\nimmediately after unregistering the framebuffer, even when an open file
\nstill holds a reference to fb_info. A concurrent driver unbind can
\ntherefore free the colormap while the ioctl copies it to userspace.<\/p>\n
KASAN reports:<\/p>\n
BUG: KASAN: slab-use-after-free in _copy_to_user
\n Read of size 512 by task poc\/125<\/p>\n
_copy_to_user (.\/include\/linux\/instrumented.h:129 .\/include\/linux\/uaccess.h:201 lib\/usercopy.c:24)
\n fb_cmap_to_user (.\/include\/linux\/uaccess.h:230 drivers\/video\/fbdev\/core\/fbcmap.c:211)
\n do_fb_ioctl (drivers\/video\/fbdev\/core\/fb_chrdev.c:114)<\/p>\n
Allocated by task 1:
\n fb_alloc_cmap_gfp (.\/include\/linux\/slab.h:973 .\/include\/linux\/slab.h:1290 drivers\/video\/fbdev\/core\/fbcmap.c:108)
\n vfb_probe (drivers\/video\/fbdev\/vfb.c:459)<\/p>\n
Freed by task 124:
\n fb_dealloc_cmap (drivers\/video\/fbdev\/core\/fbcmap.c:151)
\n vfb_remove (drivers\/video\/fbdev\/vfb.c:489)<\/p>\n
unregister_framebuffer() drops the registration reference, and fbdev calls
\nfb_destroy after the last put_fb_info(). Move the registered framebuffer’s
\ncleanup into an fb_destroy callback so its colormap and screen buffer stay
\nalive until all file references have been released.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
fbdev: vfb: defer cleanup until the last reference<\/p>\n
FBIOGETCMAP takes a shallow snapshot of info->cmap and performs the
\nusercopy af<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-29036","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/29036","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=29036"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=29036"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=29036"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}