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| author | Vivek Goyal <vgoyal@redhat.com> | 2014-08-29 15:18:29 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-08-29 16:28:15 -0700 |
| commit | 800df627e2eabaf4a921d342a1d5162c843b7fc2 (patch) | |
| tree | c4b0d687441d22c60273d7f8f54b27604696dc07 /kernel/resource.c | |
| parent | 3f6316b4378e64e96acfe55b499648dc0e6b9603 (diff) | |
| download | linux-800df627e2eabaf4a921d342a1d5162c843b7fc2.tar.gz linux-800df627e2eabaf4a921d342a1d5162c843b7fc2.tar.bz2 linux-800df627e2eabaf4a921d342a1d5162c843b7fc2.zip | |
resource: fix the case of null pointer access
Richard and Daniel reported that UML is broken due to changes to
resource traversal functions. Problem is that iomem_resource.child can
be null and new code does not consider that possibility. Old code used
a for loop and that loop will not even execute if p was null.
Revert back to for() loop logic and bail out if p is null.
I also moved sibling_only check out of resource_lock. There is no
reason to keep it inside the lock.
Following is backtrace of the UML crash.
RIP: 0033:[<0000000060039b9f>]
RSP: 0000000081459da0 EFLAGS: 00010202
RAX: 0000000000000000 RBX: 00000000219b3fff RCX: 000000006010d1d9
RDX: 0000000000000001 RSI: 00000000602dfb94 RDI: 0000000081459df8
RBP: 0000000081459de0 R08: 00000000601b59f4 R09: ffffffff0000ff00
R10: ffffffff0000ff00 R11: 0000000081459e88 R12: 0000000081459df8
R13: 00000000219b3fff R14: 00000000602dfb94 R15: 0000000000000000
Kernel panic - not syncing: Segfault with no mm
CPU: 0 PID: 1 Comm: swapper Not tainted 3.16.0-10454-g58d08e3 #13
Stack:
00000000 000080d0 81459df0 219b3fff
81459e70 6010d1d9 ffffffff 6033e010
81459e50 6003a269 81459e30 00000000
Call Trace:
[<6010d1d9>] ? kclist_add_private+0x0/0xe7
[<6003a269>] walk_system_ram_range+0x61/0xb7
[<6000e859>] ? proc_kcore_init+0x0/0xf1
[<6010d574>] kcore_update_ram+0x4c/0x168
[<6010d72e>] ? kclist_add+0x0/0x2e
[<6000e943>] proc_kcore_init+0xea/0xf1
[<6000e859>] ? proc_kcore_init+0x0/0xf1
[<6000e859>] ? proc_kcore_init+0x0/0xf1
[<600189f0>] do_one_initcall+0x13c/0x204
[<6004ca46>] ? parse_args+0x1df/0x2e0
[<6004c82d>] ? parameq+0x0/0x3a
[<601b5990>] ? strcpy+0x0/0x18
[<60001e1a>] kernel_init_freeable+0x240/0x31e
[<6026f1c0>] kernel_init+0x12/0x148
[<60019fad>] new_thread_handler+0x81/0xa3
Fixes 8c86e70acead629aacb4a ("resource: provide new functions to walk
through resources").
Reported-by: Daniel Walter <sahne@0x90.at>
Tested-by: Richard Weinberger <richard@nod.at>
Tested-by: Toralf Förster <toralf.foerster@gmx.de>
Tested-by: Daniel Walter <sahne@0x90.at>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/resource.c')
| -rw-r--r-- | kernel/resource.c | 11 |
1 files changed, 4 insertions, 7 deletions
diff --git a/kernel/resource.c b/kernel/resource.c index da14b8d09296..60c5a3856ab7 100644 --- a/kernel/resource.c +++ b/kernel/resource.c @@ -351,15 +351,12 @@ static int find_next_iomem_res(struct resource *res, char *name, end = res->end; BUG_ON(start >= end); - read_lock(&resource_lock); - - if (first_level_children_only) { - p = iomem_resource.child; + if (first_level_children_only) sibling_only = true; - } else - p = &iomem_resource; - while ((p = next_resource(p, sibling_only))) { + read_lock(&resource_lock); + + for (p = iomem_resource.child; p; p = next_resource(p, sibling_only)) { if (p->flags != res->flags) continue; if (name && strcmp(p->name, name)) |