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Imre Deak 2dcb22b346 idr: fix backtrack logic in idr_remove_all 
Currently idr_remove_all will fail with a use after free error if
idr::layers is bigger than 2, which on 32 bit systems corresponds to items
more than 1024.  This is due to stepping back too many levels during
backtracking.  For simplicity let's assume that IDR_BITS=1 -> we have 2
nodes at each level below the root node and each leaf node stores two IDs.
 (In reality for 32 bit systems IDR_BITS=5, with 32 nodes at each sub-root
level and 32 IDs in each leaf node).  The sequence of freeing the nodes at
the moment is as follows:

layer
1 ->                       a(7)
2 ->            b(3)                  c(5)
3 ->        d(1)   e(2)           f(4)    g(6)

Until step 4 things go fine, but then node c is freed, whereas node g
should be freed first.  Since node c contains the pointer to node g we'll
have a use after free error at step 6.

How many levels we step back after visiting the leaf nodes is currently
determined by the msb of the id we are currently visiting:

Step
1.          node d with IDs 0,1 is freed, current ID is advanced to 2.
            msb of the current ID bit 1. This means we need to step back
            1 level to node b and take the next sibling, node e.
2-3.        node e with IDs 2,3 is freed, current ID is 4, msb is bit 2.
            This means we need to step back 2 levels to node a, freeing
            node b on the way.
4-5.        node f with IDs 4,5 is freed, current ID is 6, msb is still
            bit 2. This means we again need to step back 2 levels to node
            a and free c on the way.
6.          We should visit node g, but its pointer is not available as
            node c was freed.

The fix changes how we determine the number of levels to step back.
Instead of deducting this merely from the msb of the current ID, we should
really check if advancing the ID causes an overflow to a bit position
corresponding to a given layer.  In the above example overflow from bit 0
to bit 1 should mean stepping back 1 level.  Overflow from bit 1 to bit 2
should mean stepping back 2 levels and so on.

The fix was tested with IDs up to 1 << 20, which corresponds to 4 layers
on 32 bit systems.

Signed-off-by: Imre Deak <imre.deak@nokia.com>
Reviewed-by: Tejun Heo <tj@kernel.org>
Cc: Eric Paris <eparis@redhat.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: <stable@kernel.org>		[2.6.34.1]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 		2010-05-27 09:12:48 -07:00
..
lzo lib: add support for LZO-compressed kernels 2010-01-11 09:34:04 -08:00
reed_solomon
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zlib_deflate trivial: fix typo "to to" in multiple files 2009-09-21 15:14:55 +02:00
zlib_inflate inflate_fast: sout is already a short so ptr arith was off by one. 2010-03-12 15:52:44 -08:00
.gitignore
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Kconfig Revert "lib: build list_sort() only if needed" 2010-03-07 09:54:44 -08:00
Kconfig.debug fault-injection: add CPU notifier error injection module 2010-05-27 09:12:48 -07:00
Kconfig.kgdb mips,kgdb: kdb low level trap catch and stack trace 2010-05-20 21:04:26 -05:00
Kconfig.kmemcheck kmemcheck: depend on HAVE_ARCH_KMEMCHECK 2009-07-01 22:28:44 +02:00
Makefile fault-injection: add CPU notifier error injection module 2010-05-27 09:12:48 -07:00
argv_split.c tree-wide: convert open calls to remove spaces to skip_spaces() lib function 2009-12-15 08:53:32 -08:00
atomic64.c lib: Fix atomic64_add_unless return value convention 2010-03-01 11:38:46 -08:00
atomic64_test.c x86, atomic64: In selftest, distinguish x86-64 from 586+ 2010-03-01 11:51:56 -08:00
audit.c
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bcd.c rtc: BCD codeshrink 2008-07-24 10:47:33 -07:00
bitmap.c cpusets: randomize node rotor used in cpuset_mem_spread_node() 2010-05-27 09:12:44 -07:00
bitrev.c lib: export bitrev16 2008-06-06 11:29:10 -07:00
btree.c lib/btree: fix possible NULL pointer dereference 2010-05-15 12:48:10 -07:00
bug.c panic: Allow warnings to set different taint flags 2010-05-19 08:36:48 +01:00
bust_spinlocks.c oops handling: ensure that any oops is flushed to the mtdoops console 2009-01-06 15:59:11 -08:00
check_signature.c
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checksum.c lib/checksum: fix one more thinko 2009-11-03 16:06:53 +01:00
cmdline.c generic, memparse(): constify argument 2008-07-28 15:05:23 +02:00
cpu-notifier-error-inject.c fault-injection: add CPU notifier error injection module 2010-05-27 09:12:48 -07:00
cpumask.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
crc-ccitt.c
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crc-itu-t.c
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crc-t10dif.c [SCSI] lib: Add support for the T10 (SCSI) Data Integrity Field CRC 2008-07-12 08:22:32 -05:00
crc7.c
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crc16.c
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crc32.c revert "crc32: use __BYTE_ORDER macro for endian detection" 2010-05-26 08:19:23 -07:00
crc32defs.h
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ctype.c ctype: constify read-only _ctype string 2009-12-15 08:53:32 -08:00
debug_locks.c rcu: Introduce lockdep-based checking to RCU read-side primitives 2010-02-25 09:40:59 +01:00
debugobjects.c Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-05-18 08:17:58 -07:00
dec_and_lock.c atomic: only take lock when the counter drops to zero on UP as well 2009-06-16 19:47:47 -07:00
decompress.c Add LZO compression support for initramfs and old-style initrd 2010-01-11 09:34:05 -08:00
decompress_bunzip2.c bzip2: Add missing checks for malloc returning NULL 2009-12-15 14:04:19 -08:00
decompress_inflate.c lzma/gzip: fix potential oops when input data is truncated 2009-09-24 07:21:05 -07:00
decompress_unlzma.c lzma/gzip: fix potential oops when input data is truncated 2009-09-24 07:21:05 -07:00
decompress_unlzo.c lib: fix the use of LZO to decompress initramfs images 2010-04-24 11:31:25 -07:00
devres.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
div64.c add an inlined version of iter_div_u64_rem 2008-06-12 10:47:58 +02:00
dma-debug.c dma-debug: Cleanup for copy-loop in filter_write() 2010-04-07 14:36:27 +02:00
dump_stack.c
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dynamic_debug.c dynamic_debug: small cleanup in ddebug_proc_write() 2010-05-25 08:07:05 -07:00
extable.c module: trim exception table on init free. 2009-06-12 21:47:04 +09:30
fault-inject.c headers: remove sched.h from interrupt.h 2009-10-11 11:20:58 -07:00
find_last_bit.c bitmap: find_last_bit() 2009-01-01 10:12:19 +10:30
find_next_bit.c
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flex_array.c flex_array: fix the panic when calling flex_array_alloc() without __GFP_ZERO 2010-04-24 11:31:24 -07:00
gcd.c lib: add lib/gcd.c 2009-06-18 13:04:05 -07:00
gen_crc32table.c crc32: major optimization 2010-05-25 08:07:06 -07:00
genalloc.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
halfmd4.c
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hexdump.c lib: introduce common method to convert hex digits 2010-05-25 08:07:05 -07:00
hweight.c x86: Add optimized popcnt variants 2010-04-06 15:52:11 -07:00
idr.c idr: fix backtrack logic in idr_remove_all 2010-05-27 09:12:48 -07:00
inflate.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
int_sqrt.c
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iomap.c Use WARN() in lib/ 2008-07-26 12:00:07 -07:00
iomap_copy.c
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iommu-helper.c iommu-helper: use bitmap library 2009-12-16 07:20:18 -08:00
ioremap.c
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irq_regs.c
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is_single_threaded.c kernel: is_current_single_threaded: don't use ->mmap_sem 2009-07-17 09:11:31 +10:00
kasprintf.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
kernel_lock.c bkl: Fixup core_lock fallout 2009-12-14 23:55:33 +01:00
klist.c driver core: Remove completion from struct klist_node 2009-01-06 10:44:30 -08:00
kobject.c sysfs: Comment sysfs directory tagging logic 2010-05-21 09:37:31 -07:00
kobject_uevent.c hotplug: netns aware uevent_helper 2010-05-21 09:37:33 -07:00
kref.c kref: remove kref_set 2010-05-21 09:37:29 -07:00
lcm.c block: Fix overrun in lcm() and move it to lib 2010-03-15 12:47:59 +01:00
libcrc32c.c libcrc32c: Fix "crc32c undefined" compilation error 2008-12-25 11:01:42 +11:00
list_debug.c list debugging: use WARN() instead of BUG() 2008-07-25 10:53:29 -07:00
list_sort.c lib: revise list_sort() header comment 2010-03-06 11:26:35 -08:00
lmb.c lmb: Add lmb_free() 2010-02-03 17:39:50 +11:00
locking-selftest-hardirq.h
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locking-selftest-mutex.h
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locking-selftest-rlock-hardirq.h
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locking-selftest-rlock-softirq.h
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locking-selftest-rlock.h
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locking-selftest-rsem.h
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locking-selftest-softirq.h
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locking-selftest-spin-hardirq.h
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locking-selftest-spin-softirq.h
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locking-selftest-spin.h
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locking-selftest-wlock-hardirq.h
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locking-selftest-wlock-softirq.h
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locking-selftest-wlock.h
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locking-selftest-wsem.h
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locking-selftest.c locking: rename trace_softirq_[enter|exit] => lockdep_softirq_[enter|exit] 2009-03-13 01:32:36 +01:00
lru_cache.c The DRBD driver 2009-10-01 21:17:49 +02:00
nlattr.c Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/kaber/nf-next-2.6 2009-03-26 22:45:23 -07:00
parser.c parser: remove unnecessary strlen() 2009-12-15 08:53:33 -08:00
percpu_counter.c Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-01-06 17:10:04 -08:00
plist.c plist: Make plist debugging raw_spinlock aware 2009-12-14 23:55:33 +01:00
prio_heap.c lib: fix sparse shadowed variable warning 2009-01-06 15:59:11 -08:00
prio_tree.c
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proportions.c Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-01-06 17:10:04 -08:00
radix-tree.c radix_tree_tag_get() is not as safe as the docs make out [ver #2] 2010-04-09 10:12:03 -07:00
random32.c random32: seeding improvement 2008-07-30 16:29:19 -07:00
ratelimit.c ratelimit: fix the return value when __ratelimit() fails to acquire the lock 2010-04-07 08:38:04 -07:00
rational.c lib/rational.c needs module.h 2010-01-11 09:34:05 -08:00
rbtree.c rbtree: Add support for augmented rbtrees 2010-02-18 15:40:56 -08:00
reciprocal_div.c
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rwsem-spinlock.c rwsem generic spinlock: use IRQ save/restore spinlocks 2010-04-07 16:15:05 -07:00
rwsem.c rwsem: Test for no active locks in __rwsem_do_wake undo code 2010-05-12 18:23:34 -07:00
scatterlist.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
sha1.c
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show_mem.c mm: use the same log level for show_mem() 2010-03-06 11:26:27 -08:00
smp_processor_id.c cpumask: convert lib/smp_processor_id to new cpumask ops 2009-01-30 15:47:34 +01:00
sort.c generic swap(): lib/sort.c: rename swap to swap_func 2009-01-08 08:31:14 -08:00
spinlock_debug.c locking: Further name space cleanups 2009-12-14 23:55:33 +01:00
string.c lib/string.c: simplify strnstr() 2010-03-06 11:26:35 -08:00
string_helpers.c [SCSI] lib: string_get_size(): don't hang on zero; no decimals on exact 2008-10-23 11:42:20 -05:00
swiotlb.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
syscall.c task_current_syscall 2008-07-26 12:00:10 -07:00
textsearch.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
ts_bm.c textsearch: ts_bm: support case insensitive searching in Boyer-Moore algorithm 2008-07-08 02:37:54 -07:00
ts_fsm.c textsearch: ts_fsm: return error on request for case insensitive search 2008-07-08 02:38:27 -07:00
ts_kmp.c textsearch: ts_kmp: support case insensitive searching in Knuth-Morris-Pratt algorithm 2008-07-08 02:38:09 -07:00
vsprintf.c vsprintf.c: use noinline_for_stack 2010-05-25 08:07:04 -07:00