[Ocfs2-tools-devel] [RFC] PATCH: verify slot number in __ocfs2_read_slot_map(), v2
Sunil Mushran
sunil.mushran at oracle.com
Wed Mar 11 12:11:48 PDT 2009
Slot numbers and node numbers are not the same. That comparison is
incorrect. I don't remember the macro offhand. Check out the node
manager code in the kernel.
On Thu, Mar 12, 2009 at 12:47:34AM +0800, Coly Li wrote:
> In some buggy conditions, mounted.ocfs2 does dirty reads, data from
> __ocfs2_read_slot_map() can not be trusted. When it happens, in ocfs2_print_nodes():
> 66 node_num = map->md_slots[i].sd_node_num;
> 67 if (names && names[node_num] && *(names[node_num]))
> node_num in 66 may be a very large number (due to the invalid data from
> __ocfs2_read_slot_map()), and names[node_num] references to an illegal memory
> region.
>
> This patch adds two functions to check whether slot number of each read-in slot
> map item is valid, which can avoid a segmentation fault of mounted.ocfs2 with an
> error message:
> __ocfs2_verify_node_num() for normal slot map item checking
> __ocfs2_verify_node_num_extended() for extended slot map item checking
>
> Currently, this patch makes mounted.ocfs2 display error message in this style:
> # mounted.ocfs2 -f
> Device FS Nodes
> /dev/hdb1 ocfs2 Unknown: Internal logic faliure
>
> There will be another patch to improve/fix the error message, e.g. from Sunil's
> suggestion, just displaying "Unknow" in Nodes field.
>
> Signed-off-by: Coly Li <coly.li at suse.de>
> ---
> libocfs2/slot_map.c | 27 ++++++++++++++++++++++++++-
> 1 files changed, 26 insertions(+), 1 deletions(-)
>
> diff --git a/libocfs2/slot_map.c b/libocfs2/slot_map.c
> index c33f458..e8d22a1 100644
> --- a/libocfs2/slot_map.c
> +++ b/libocfs2/slot_map.c
> @@ -54,6 +54,29 @@ void ocfs2_swap_slot_map_extended(struct
> ocfs2_slot_map_extended *se,
> bswap_32(se->se_slots[i].es_node_num);
> }
>
> +/* es_node_num should be swapped to local cpu endian */
> +static errcode_t __ocfs2_verify_node_num(struct ocfs2_slot_map *sm,
> + int num_slots)
> +{
> + int i;
> +
> + for (i = 0; i < num_slots; i++)
> + if (sm->sm_slots[i] > OCFS2_MAX_SLOTS)
> + return OCFS2_ET_INTERNAL_FAILURE;
> + return 0;
> +}
> +
> +/* es_node_num should be swapped to local cpu endian */
> +static errcode_t __ocfs2_verify_node_num_extended(struct
> ocfs2_slot_map_extended *se,
> + int num_slots)
> +{
> + int i;
> + for (i = 0; i < num_slots; i++)
> + if (se->se_slots[i].es_node_num > OCFS2_MAX_SLOTS)
> + return OCFS2_ET_INTERNAL_FAILURE;
> + return 0;
> +}
> +
> static errcode_t __ocfs2_read_slot_map(ocfs2_filesys *fs,
> int num_slots,
> union ocfs2_slot_map_wrapper *wrap)
> @@ -90,13 +113,15 @@ static errcode_t __ocfs2_read_slot_map(ocfs2_filesys *fs,
> se = (struct ocfs2_slot_map_extended *)slot_map_buf;
> ocfs2_swap_slot_map_extended(se, num_slots);
> wrap->mw_map_extended = se;
> + ret = __ocfs2_verify_node_num_extended(se, num_slots);
> } else {
> sm = (struct ocfs2_slot_map *)slot_map_buf;
> ocfs2_swap_slot_map(sm, num_slots);
> wrap->mw_map = sm;
> + ret = __ocfs2_verify_node_num(sm, num_slots);
> }
>
> - return 0;
> + return ret;
> }
>
> errcode_t ocfs2_read_slot_map(ocfs2_filesys *fs,
>
> --
> Coly Li
> SuSE Labs
>
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