[Crash-utility] [PATCH] fix read size in xendump.c
Dave Anderson
anderson at redhat.com
Wed Aug 29 14:07:25 UTC 2007
Dave Anderson wrote:
> Isaku Yamahata wrote:
>
>> Hi.
>> Recently I twisted the xen xm dump-core format so that the section
>> order was changed for optimization.
>> Although it shouldn't affect analysis tools, it revealed a bug.
>> The crash utility tries to read the file beyond EOF.
>> So far it wasn't issue because of section ordering.
>> This patch fixes it by calculating read size correctly
>>
>
> The crash patch looks reasonable. But when you state that
> "So far it wasn't issue because of section ordering", it
> would seem that just the opposite would be true? Since the
> .xen_pages section has been moved closer to the beginning
> of the dumpfile, it would seem that the EOF read error would
> be *more likely* when using the older dumpfile format, where
> the .xen_pages section was located closer to the end of the
> dumpfile?
Sorry -- I misunderstood -- it's not the .xen_pages data
that it's reading, but rather the p2m list.
The patch looks good... ;-)
>
>
>> Dave, Although I don't think that it causes serious issues,
>> Could you check whether the minor update of the format affects
>> the crash utility?
>> http://article.gmane.org/gmane.comp.emulators.xen.ia64/7531
>> http://article.gmane.org/gmane.comp.emulators.xen.devel/42996
>
>
> You'd have to make some sample dumpfiles available to me
> to verify the new format.
>
> I'm more concerned at the moment for backwards-compatibility, i.e.,
> whether the crash patch will still work OK with the "older" xen
> ELF core format, which will be used in the RHEL5.1 update,
> and possibly beyond that.
>
> Thanks,
> Dave
>
>>
>>
>> --- crash-4.0-4.6-ORIG/xendump.c 2007-08-28 00:51:11.000000000 +0900
>> +++ ./crash-4.0-4.6/xendump.c 2007-08-29 18:14:05.000000000 +0900
>> @@ -1289,9 +1289,8 @@ xc_core_mfn_to_page(ulong mfn, char *pgb
>>
>> for (b = 0, idx = -1, done = FALSE; !done && (b <
>> nr_pages); b += MAX_BATCH_SIZE) {
>> -
>> - if (read(xd->xfd, tmp, sizeof(ulong) *
>> MAX_BATCH_SIZE) != - (MAX_BATCH_SIZE * sizeof(ulong))) {
>> + size_t size = sizeof(ulong) * MIN(MAX_BATCH_SIZE, nr_pages - b);
>> + if (read(xd->xfd, tmp, size) != size) {
>> error(INFO, "cannot read index page %d\n", b);
>> return NULL;
>> }
>> @@ -1348,13 +1347,11 @@ xc_core_elf_mfn_to_page(ulong mfn, char {
>> int i, b, idx, done;
>> off_t offset;
>> - size_t size;
>> uint nr_pages;
>> ulong tmp;
>> struct xen_dumpcore_p2m p2m_batch[MAX_BATCH_SIZE];
>>
>> offset = xd->xc_core.header.xch_index_offset;
>> - size = sizeof(struct xen_dumpcore_p2m) * MAX_BATCH_SIZE;
>> nr_pages = xd->xc_core.header.xch_nr_pages;
>>
>> if (lseek(xd->xfd, offset, SEEK_SET) == -1)
>> @@ -1362,7 +1359,8 @@ xc_core_elf_mfn_to_page(ulong mfn, char
>> for (b = 0, idx = -1, done = FALSE; !done && (b <
>> nr_pages); b += MAX_BATCH_SIZE) {
>> -
>> + size_t size = sizeof(struct xen_dumpcore_p2m) *
>> + MIN(MAX_BATCH_SIZE, nr_pages - b);
>> if (read(xd->xfd, &p2m_batch[0], size) != size) {
>> error(INFO, "cannot read index page %d\n", b);
>> return NULL;
>> @@ -1437,9 +1435,9 @@ xc_core_mfn_to_page_index(ulong mfn)
>> nr_pages *= 2;
>>
>> for (b = 0; b < nr_pages; b += MAX_BATCH_SIZE) {
>> -
>> - if (read(xd->xfd, tmp, sizeof(ulong) *
>> MAX_BATCH_SIZE) != - (MAX_BATCH_SIZE * sizeof(ulong))) {
>> + size_t size =
>> + sizeof(ulong) * MIN(MAX_BATCH_SIZE, nr_pages - b);
>> + if (read(xd->xfd, tmp, size) != size) {
>> error(INFO, "cannot read index page %d\n", b);
>> return MFN_NOT_FOUND;
>> }
>> @@ -1469,20 +1467,19 @@ xc_core_elf_mfn_to_page_index(ulong mfn)
>> {
>> int i, b;
>> off_t offset;
>> - size_t size;
>> uint nr_pages;
>> ulong tmp;
>> struct xen_dumpcore_p2m p2m_batch[MAX_BATCH_SIZE];
>>
>> offset = xd->xc_core.header.xch_index_offset;
>> - size = sizeof(struct xen_dumpcore_p2m) * MAX_BATCH_SIZE;
>> nr_pages = xd->xc_core.header.xch_nr_pages;
>>
>> if (lseek(xd->xfd, offset, SEEK_SET) == -1)
>> error(FATAL, "cannot lseek to page index\n");
>>
>> for (b = 0; b < nr_pages; b += MAX_BATCH_SIZE) {
>> -
>> + size_t size = sizeof(struct xen_dumpcore_p2m) *
>> + MIN(MAX_BATCH_SIZE, nr_pages - b);
>> if (read(xd->xfd, &p2m_batch[0], size) != size) {
>> error(INFO, "cannot read index page %d\n", b);
>> return MFN_NOT_FOUND;
>> @@ -1563,8 +1560,9 @@ check_next_4:
>> nr_pages = xd->xc_core.header.xch_nr_pages;
>>
>> for (b = 0; b < nr_pages; b += MAX_BATCH_SIZE) {
>> - if (read(xd->xfd, tmp, sizeof(ulong) *
>> MAX_BATCH_SIZE) !=
>> - (MAX_BATCH_SIZE * sizeof(ulong))) {
>> + size_t size = sizeof(ulong) *
>> + MIN(MAX_BATCH_SIZE, nr_pages - b);
>> + if (read(xd->xfd, tmp, size) != size) {
>> error(INFO, "cannot read index page
>> %d\n", b);
>> return FALSE;
>> }
>> @@ -1595,8 +1593,9 @@ show_64bit_mfns:
>> nr_pages = xd->xc_core.header.xch_nr_pages;
>>
>> for (b = 0; b < nr_pages; b += MAX_BATCH_SIZE) {
>> - if (read(xd->xfd, tmp64, sizeof(ulonglong) *
>> MAX_BATCH_SIZE) !=
>> - (MAX_BATCH_SIZE * sizeof(ulonglong))) {
>> + size_t size = sizeof(ulonglong) *
>> + MIN(MAX_BATCH_SIZE, nr_pages - b);
>> + if (read(xd->xfd, tmp64, size) != size) {
>> error(INFO, "cannot read index page
>> %d\n", b);
>> return FALSE;
>> }
>> @@ -1709,13 +1708,11 @@ xc_core_elf_pfn_to_page_index(ulong pfn)
>> {
>> int i, b, start_index;
>> off_t offset;
>> - size_t size;
>> uint nr_pages;
>> ulong tmp;
>> struct xen_dumpcore_p2m p2m_batch[MAX_BATCH_SIZE];
>>
>> offset = xd->xc_core.header.xch_index_offset;
>> - size = sizeof(struct xen_dumpcore_p2m) * MAX_BATCH_SIZE;
>> nr_pages = xd->xc_core.header.xch_nr_pages;
>>
>> /*
>> @@ -1744,7 +1741,8 @@ xc_core_elf_pfn_to_page_index(ulong pfn)
>> error(FATAL, "cannot lseek to page index\n");
>>
>> for (b = start_index; b < nr_pages; b += MAX_BATCH_SIZE) {
>> -
>> + size_t size = sizeof(struct xen_dumpcore_p2m) *
>> + MIN(MAX_BATCH_SIZE, nr_pages - b);
>> if (read(xd->xfd, &p2m_batch[0], size) != size) {
>> error(INFO, "cannot read index page %d\n", b);
>> return PFN_NOT_FOUND;
>> @@ -1838,13 +1836,11 @@ xc_core_elf_pfn_valid(ulong pfn)
>> {
>> int i, b, start_index;
>> off_t offset;
>> - size_t size;
>> uint nr_pages;
>> ulong tmp;
>> uint64_t pfn_batch[MAX_BATCH_SIZE];
>>
>> offset = xd->xc_core.header.xch_index_offset;
>> - size = sizeof(uint64_t) * MAX_BATCH_SIZE;
>> nr_pages = xd->xc_core.header.xch_nr_pages;
>>
>> /*
>> @@ -1873,7 +1869,8 @@ xc_core_elf_pfn_valid(ulong pfn)
>> error(FATAL, "cannot lseek to page index\n");
>>
>> for (b = start_index; b < nr_pages; b += MAX_BATCH_SIZE) {
>> -
>> + size_t size = sizeof(uint64_t) *
>> + MIN(MAX_BATCH_SIZE, nr_pages - b);
>> if (read(xd->xfd, &pfn_batch[0], size) != size) {
>> error(INFO, "cannot read index page %d\n", b);
>> return PFN_NOT_FOUND;
>>
>
>
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