linux/lib, branch v3.4.45

kobject: fix kset_find_obj() race with concurrent last kobject_put()

2013-04-17T04:27:27Z

commit a49b7e82cab0f9b41f483359be83f44fbb6b4979 upstream. Anatol Pomozov identified a race condition that hits module unloading and re-loading. To quote Anatol: "This is a race codition that exists between kset_find_obj() and kobject_put(). kset_find_obj() might return kobject that has refcount equal to 0 if this kobject is freeing by kobject_put() in other thread. Here is timeline for the crash in case if kset_find_obj() searches for an object tht nobody holds and other thread is doing kobject_put() on the same kobject: THREAD A (calls kset_find_obj()) THREAD B (calls kobject_put()) splin_lock() atomic_dec_return(kobj->kref), counter gets zero here ... starts kobject cleanup .... spin_lock() // WAIT thread A in kobj_kset_leave() iterate over kset->list atomic_inc(kobj->kref) (counter becomes 1) spin_unlock() spin_lock() // taken // it does not know that thread A increased counter so it remove obj from list spin_unlock() vfree(module) // frees module object with containing kobj // kobj points to freed memory area!! kobject_put(kobj) // OOPS!!!! The race above happens because module.c tries to use kset_find_obj() when somebody unloads module. The module.c code was introduced in commit 6494a93d55fa" Anatol supplied a patch specific for module.c that worked around the problem by simply not using kset_find_obj() at all, but rather than make a local band-aid, this just fixes kset_find_obj() to be thread-safe using the proper model of refusing the get a new reference if the refcount has already dropped to zero. See examples of this proper refcount handling not only in the kref documentation, but in various other equivalent uses of this pattern by grepping for atomic_inc_not_zero(). [ Side note: the module race does indicate that module loading and unloading is not properly serialized wrt sysfs information using the module mutex. That may require further thought, but this is the correct fix at the kobject layer regardless. ] Reported-analyzed-and-tested-by: Anatol Pomozov Cc: Al Viro Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

idr: fix a subtle bug in idr_get_next()

2013-03-03T22:06:40Z

commit 6cdae7416a1c45c2ce105a78187d9b7e8feb9e24 upstream. The iteration logic of idr_get_next() is borrowed mostly verbatim from idr_for_each(). It walks down the tree looking for the slot matching the current ID. If the matching slot is not found, the ID is incremented by the distance of single slot at the given level and repeats. The implementation assumes that during the whole iteration id is aligned to the layer boundaries of the level closest to the leaf, which is true for all iterations starting from zero or an existing element and thus is fine for idr_for_each(). However, idr_get_next() may be given any point and if the starting id hits in the middle of a non-existent layer, increment to the next layer will end up skipping the same offset into it. For example, an IDR with IDs filled between [64, 127] would look like the following. [ 0 64 ... ] /----/ | | | NULL [ 64 ... 127 ] If idr_get_next() is called with 63 as the starting point, it will try to follow down the pointer from 0. As it is NULL, it will then try to proceed to the next slot in the same level by adding the slot distance at that level which is 64 - making the next try 127. It goes around the loop and finds and returns 127 skipping [64, 126]. Note that this bug also triggers in idr_for_each_entry() loop which deletes during iteration as deletions can make layers go away leaving the iteration with unaligned ID into missing layers. Fix it by ensuring proceeding to the next slot doesn't carry over the unaligned offset - ie. use round_up(id + 1, slot_distance) instead of id += slot_distance. Signed-off-by: Tejun Heo Reported-by: David Teigland Cc: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

digsig: Fix memory leakage in digsig_verify_rsa()

2013-02-11T16:47:17Z

commit 7810cc1e7721220f1ed2a23ca95113d6434f6dcd upstream. digsig_verify_rsa() does not free kmalloc'ed buffer returned by mpi_get_buffer(). Signed-off-by: YOSHIFUJI Hideaki Signed-off-by: Dmitry Kasatkin Signed-off-by: James Morris Signed-off-by: Greg Kroah-Hartman

lib: atomic64: Initialize locks statically to fix early users

2013-01-11T17:07:17Z

commit fcc16882ac4532aaa644bff444f0c5d6228ba71e upstream. The atomic64 library uses a handful of static spin locks to implement atomic 64-bit operations on architectures without support for atomic 64-bit instructions. Unfortunately, the spinlocks are initialized in a pure initcall and that is too late for the vfs namespace code which wants to use atomic64 operations before the initcall is run. This became a problem as of commit 8823c079ba71: "vfs: Add setns support for the mount namespace". This leads to BUG messages such as: BUG: spinlock bad magic on CPU#0, swapper/0/0 lock: atomic64_lock+0x240/0x400, .magic: 00000000, .owner: /-1, .owner_cpu: 0 do_raw_spin_lock+0x158/0x198 _raw_spin_lock_irqsave+0x4c/0x58 atomic64_add_return+0x30/0x5c alloc_mnt_ns.clone.14+0x44/0xac create_mnt_ns+0xc/0x54 mnt_init+0x120/0x1d4 vfs_caches_init+0xe0/0x10c start_kernel+0x29c/0x300 coming out early on during boot when spinlock debugging is enabled. Fix this by initializing the spinlocks statically at compile time. Reported-and-tested-by: Vaibhav Bedia Tested-by: Tony Lindgren Cc: Eric W. Biederman Signed-off-by: Stephen Boyd Signed-off-by: Linus Torvalds Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

MPI: Fix compilation on MIPS with GCC 4.4 and newer

2012-12-03T19:47:23Z

commit a3cea9894157c20a5b1ec08b7e0b5f2019740c10 upstream. Since 4.4 GCC on MIPS no longer recognizes the "h" constraint, leading to this build failure: CC lib/mpi/generic_mpih-mul1.o lib/mpi/generic_mpih-mul1.c: In function 'mpihelp_mul_1': lib/mpi/generic_mpih-mul1.c:50:3: error: impossible constraint in 'asm' This patch updates MPI with the latest umul_ppm implementations for MIPS. Signed-off-by: Manuel Lauss Cc: Linux-MIPS Cc: Dmitry Kasatkin Cc: James Morris Patchwork: https://patchwork.linux-mips.org/patch/4612/ Signed-off-by: Ralf Baechle Cc: Shuah Khan Signed-off-by: Greg Kroah-Hartman

genalloc: stop crashing the system when destroying a pool

2012-10-31T17:02:56Z

commit eedce141cd2dad8d0cefc5468ef41898949a7031 upstream. The genalloc code uses the bitmap API from include/linux/bitmap.h and lib/bitmap.c, which is based on long values. Both bitmap_set from lib/bitmap.c and bitmap_set_ll, which is the lockless version from genalloc.c, use BITMAP_LAST_WORD_MASK to set the first bits in a long in the bitmap. That one uses (1 << bits) - 1, 0b111, if you are setting the first three bits. This means that the API counts from the least significant bits (LSB from now on) to the MSB. The LSB in the first long is bit 0, then. The same works for the lookup functions. The genalloc code uses longs for the bitmap, as it should. In include/linux/genalloc.h, struct gen_pool_chunk has unsigned long bits[0] as its last member. When allocating the struct, genalloc should reserve enough space for the bitmap. This should be a proper number of longs that can fit the amount of bits in the bitmap. However, genalloc allocates an integer number of bytes that fit the amount of bits, but may not be an integer amount of longs. 9 bytes, for example, could be allocated for 70 bits. This is a problem in itself if the Least Significat Bit in a long is in the byte with the largest address, which happens in Big Endian machines. This means genalloc is not allocating the byte in which it will try to set or check for a bit. This may end up in memory corruption, where genalloc will try to set the bits it has not allocated. In fact, genalloc may not set these bits because it may find them already set, because they were not zeroed since they were not allocated. And that's what causes a BUG when gen_pool_destroy is called and check for any set bits. What really happens is that genalloc uses kmalloc_node with __GFP_ZERO on gen_pool_add_virt. With SLAB and SLUB, this means the whole slab will be cleared, not only the requested bytes. Since struct gen_pool_chunk has a size that is a multiple of 8, and slab sizes are multiples of 8, we get lucky and allocate and clear the right amount of bytes. Hower, this is not the case with SLOB or with older code that did memset after allocating instead of using __GFP_ZERO. So, a simple module as this (running 3.6.0), will cause a crash when rmmod'ed. [root@phantom-lp2 foo]# cat foo.c #include #include #include #include MODULE_LICENSE("GPL"); MODULE_VERSION("0.1"); static struct gen_pool *foo_pool; static __init int foo_init(void) { int ret; foo_pool = gen_pool_create(10, -1); if (!foo_pool) return -ENOMEM; ret = gen_pool_add(foo_pool, 0xa0000000, 32 << 10, -1); if (ret) { gen_pool_destroy(foo_pool); return ret; } return 0; } static __exit void foo_exit(void) { gen_pool_destroy(foo_pool); } module_init(foo_init); module_exit(foo_exit); [root@phantom-lp2 foo]# zcat /proc/config.gz | grep SLOB CONFIG_SLOB=y [root@phantom-lp2 foo]# insmod ./foo.ko [root@phantom-lp2 foo]# rmmod foo ------------[ cut here ]------------ kernel BUG at lib/genalloc.c:243! cpu 0x4: Vector: 700 (Program Check) at [c0000000bb0e7960] pc: c0000000003cb50c: .gen_pool_destroy+0xac/0x110 lr: c0000000003cb4fc: .gen_pool_destroy+0x9c/0x110 sp: c0000000bb0e7be0 msr: 8000000000029032 current = 0xc0000000bb0e0000 paca = 0xc000000006d30e00 softe: 0 irq_happened: 0x01 pid = 13044, comm = rmmod kernel BUG at lib/genalloc.c:243! [c0000000bb0e7ca0] d000000004b00020 .foo_exit+0x20/0x38 [foo] [c0000000bb0e7d20] c0000000000dff98 .SyS_delete_module+0x1a8/0x290 [c0000000bb0e7e30] c0000000000097d4 syscall_exit+0x0/0x94 --- Exception: c00 (System Call) at 000000800753d1a0 SP (fffd0b0e640) is in userspace Signed-off-by: Thadeu Lima de Souza Cascardo Cc: Paul Gortmaker Cc: Benjamin Gaignard Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

lib/gcd.c: prevent possible div by 0

2012-10-12T20:38:38Z

commit e96875677fb2b7cb739c5d7769824dff7260d31d upstream. Account for all properties when a and/or b are 0: gcd(0, 0) = 0 gcd(a, 0) = a gcd(0, b) = b Fixes no known problems in current kernels. Signed-off-by: Davidlohr Bueso Cc: Eric Dumazet Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

digsig: add hash size comparision on signature verification

2012-10-02T17:29:55Z

commit bc01637a80f5b670bd70a0279d3f93fa8de1c96d upstream. When pkcs_1_v1_5_decode_emsa() returns without error and hash sizes do not match, hash comparision is not done and digsig_verify_rsa() returns no error. This is a bug and this patch fixes it. The bug was introduced in v3.3 by commit b35e286a640f ("lib/digsig: pkcs_1_v1_5_decode_emsa cleanup"). Signed-off-by: Dmitry Kasatkin Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

bql: Avoid possible inconsistent calculation.

2012-07-16T16:03:43Z

[ Upstream commit 914bec1011a25f65cdc94988a6f974bfb9a3c10d ] dql->num_queued could change while processing dql_completed(). To provide consistent calculation, added an on stack variable. Signed-off-by: Hiroaki SHIMODA Cc: Tom Herbert Cc: Eric Dumazet Cc: Denys Fedoryshchenko Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

bql: Avoid unneeded limit decrement.

2012-07-16T16:03:43Z

[ Upstream commit 25426b794efdc70dde7fd3134dc56fac3e7d562d ] When below pattern is observed, TIME dql_queued() dql_completed() | a) initial state | | b) X bytes queued V c) Y bytes queued d) X bytes completed e) Z bytes queued f) Y bytes completed a) dql->limit has already some value and there is no in-flight packet. b) X bytes queued. c) Y bytes queued and excess limit. d) X bytes completed and dql->prev_ovlimit is set and also dql->prev_num_queued is set Y. e) Z bytes queued. f) Y bytes completed. inprogress and prev_inprogress are true. At f), according to the comment, all_prev_completed becomes true and limit should be increased. But POSDIFF() ignores (completed == dql->prev_num_queued) case, so limit is decreased. Signed-off-by: Hiroaki SHIMODA Cc: Tom Herbert Cc: Eric Dumazet Cc: Denys Fedoryshchenko Acked-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman