Messages in this thread | | | Date | Tue, 27 May 2008 16:00:31 +0200 | From | Eric Sesterhenn <> | Subject | Re: Redzone overwritten with CONFIG_SECURITY |
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hi,
i tested a kmemcheck kernel as an attempt to debug this further... seems CONFIG_SECURITY is unrelated to this, but slub debugging only catches the overwrite it if i enable CONFIG_SECURITY.
with slub_debug=FZPU i get the warning at init_object+0x63:
(gdb) l *(init_object+0x63) 0xc0187243 is in init_object (mm/slub.c:544). 539 { 540 u8 *p = object; 541 542 if (s->flags & __OBJECT_POISON) { 543 memset(p, POISON_FREE, s->objsize - 1); 544 p[s->objsize - 1] = POISON_END; 545 } 546 547 if (s->flags & SLAB_RED_ZONE) 548 memset(p + s->objsize,
if i set slub_debug=- i get the kmemcheck warning at
(gdb) l *(__slab_alloc+0x238) 0xc0187bc8 is in __slab_alloc (mm/slub.c:303). 298 return *(void **)(object + s->offset); 299 } 300 301 static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp) 302 { 303 *(void **)(object + s->offset) = fp; 304 } 305 306 /* Loop over all objects in a slab */ 307 #define for_each_object(__p, __s, __addr, __objects) \
I used the kmemcheck git tree from git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-kmemcheck-4.git
In case you need some of the other kmemcheck output please let me know.
Greetings, Eric
* Eric Sesterhenn (snakebyte@gmx.de) wrote: > hi, > > i enabled CONFIG_SECURITY on current git and get tons of > Redzone overwritten errors during early boot, even > with CONFIG_SECURITY_CAPABILITIES and CONFIG_SECURITY_NETWORK > disabled. After a while it ends with a kernel panic > saying: not syncing: Out of memory and no killable process... > Root partition is ext3 format. > > At the moment i dont have a camera at hand, so i'll try > to write down everything which looks interesting, please tell > me if i missed something. > > The first 24 Bytes of the overwritten section contain > zeros. Then we have a constant 0x18, and three changing > values. the next three bites contain exactly the same > values, first the 0x18, then the two changing ones. > > The only value i found so far matching the 0x18 and > which might be related to CONFIG_SECURITY is CAP_SYS_RESOURCE > defined in /include/linux/capability.h > > BUG hugetlbfs_inode_cache: Redzone overwritten > > INFO: 0xccd8e250-0xccd8e253. First byte 0x0 instead of 0xbb > Info: Slab 0xc119d1c0 objects=12 used=0 fs=0xccd8e000 flags=0x400020c3 > Info: Object 0xccd8e00 offset=0 fp=0xccd8e280 > > Object 0xccd8e00: 00 00 00 ... > Object 0xccd8e10: 00 00 00 00 00 00 00 00 00 18 e0 d8 cc 18 e0 d8 cc > Object 0xccd8e20 00 00 00 ... > ... > > Pid: 1, comm:swapper Not tainted 2.6.26-rc3-00436-gb373303 #42 > print_trailer > check_bytes_and_report > check_object > __slab_alloc > kmem_cache_alloc > ? hugetlbfs_alloc_inode > ? hugetlbfs_alloc_inode > hugetlbfs_alloc_inode > alloc_inote > new_inode > hugetlbs_get_inote > hugetlbfs_fill_super > ? sget > ? set_anon_super > get_sb_node > hugetlbfs_get_sb > ? hugetlbfs_fill_super > vfs_kern_mount > kern_mount_data > init_hugetlbfs_fs > ? init_once > ? kernel_init > kernel_init
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