[Xen-changelog] [xen stable-4.2] ACPI: Prevent acpi_table_entries from falling into a infinite loop

[patchbot@xxxxxxx]

commit 590a83af39dff98e10928a4188c452729996cc22
Author:     Malcolm Crossley <malcolm.crossley@xxxxxxxxxx>
AuthorDate: Tue Jun 24 10:01:38 2014 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Jun 24 10:01:38 2014 +0200

    ACPI: Prevent acpi_table_entries from falling into a infinite loop
    
    If a buggy BIOS programs an ACPI table with to small an entry length
    then acpi_table_entries gets stuck in an infinite loop.
    
    To aid debugging, report the error and exit the loop.
    
    Based on Linux kernel commit 369d913b242cae2205471b11b6e33ac368ed33ec
    
    Signed-off-by: Malcolm Crossley <malcolm.crossley@xxxxxxxxxx>
    
    Use < instead of <= (which I wrongly suggested), return -ENODATA
    instead of -EINVAL, and make description match code.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    master commit: 9c1e8cae657bc13e8b1ddeede17603d77f3ad341
    master date: 2014-06-04 11:26:15 +0200
---
 xen/drivers/acpi/tables.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/xen/drivers/acpi/tables.c b/xen/drivers/acpi/tables.c
index e1c421e..7c31480 100644
--- a/xen/drivers/acpi/tables.c
+++ b/xen/drivers/acpi/tables.c
@@ -235,6 +235,12 @@ acpi_table_parse_entries(char *id,
 
        while (((unsigned long)entry) + sizeof(struct acpi_subtable_header) <
               table_end) {
+               if (entry->length < sizeof(*entry)) {
+                       printk(KERN_ERR PREFIX "[%4.4s:%#x] Invalid length\n",
+                              id, entry_id);
+                       return -ENODATA;
+               }
+
                if (entry->type == entry_id
                    && (!max_entries || count++ < max_entries))
                        if (handler(entry, table_end))
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.2

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