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authorRussell Currey <ruscur@russell.cc>2017-04-19 17:39:26 +1000
committerMichael Ellerman <mpe@ellerman.id.au>2017-05-02 22:41:43 +1000
commitdaeba2956f32f91f3493788ff6ee02fb1b2f02fa (patch)
tree8c87a0fdeb9e2078a24846ea41c0a242daf0c26a /arch/powerpc
parenta715626a8e904e7226915d1bc4885317ea9da141 (diff)
powerpc/eeh: Avoid use after free in eeh_handle_special_event()
eeh_handle_special_event() is called when an EEH event is detected but can't be narrowed down to a specific PE. This function looks through every PE to find one in an erroneous state, then calls the regular event handler eeh_handle_normal_event() once it knows which PE has an error. However, if eeh_handle_normal_event() found that the PE cannot possibly be recovered, it will free it, rendering the passed PE stale. This leads to a use after free in eeh_handle_special_event() as it attempts to clear the "recovering" state on the PE after eeh_handle_normal_event() returns. Thus, make sure the PE is valid when attempting to clear state in eeh_handle_special_event(). Fixes: 8a6b1bc70dbb ("powerpc/eeh: EEH core to handle special event") Cc: stable@vger.kernel.org # v3.11+ Reported-by: Alexey Kardashevskiy <aik@ozlabs.ru> Signed-off-by: Russell Currey <ruscur@russell.cc> Reviewed-by: Gavin Shan <gwshan@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc')
-rw-r--r--arch/powerpc/kernel/eeh_driver.c19
1 files changed, 15 insertions, 4 deletions
diff --git a/arch/powerpc/kernel/eeh_driver.c b/arch/powerpc/kernel/eeh_driver.c
index b94887165a10..e50d1470714f 100644
--- a/arch/powerpc/kernel/eeh_driver.c
+++ b/arch/powerpc/kernel/eeh_driver.c
@@ -724,7 +724,7 @@ static int eeh_reset_device(struct eeh_pe *pe, struct pci_bus *bus,
*/
#define MAX_WAIT_FOR_RECOVERY 300
-static void eeh_handle_normal_event(struct eeh_pe *pe)
+static bool eeh_handle_normal_event(struct eeh_pe *pe)
{
struct pci_bus *frozen_bus;
struct eeh_dev *edev, *tmp;
@@ -736,7 +736,7 @@ static void eeh_handle_normal_event(struct eeh_pe *pe)
if (!frozen_bus) {
pr_err("%s: Cannot find PCI bus for PHB#%x-PE#%x\n",
__func__, pe->phb->global_number, pe->addr);
- return;
+ return false;
}
eeh_pe_update_time_stamp(pe);
@@ -870,7 +870,7 @@ static void eeh_handle_normal_event(struct eeh_pe *pe)
pr_info("EEH: Notify device driver to resume\n");
eeh_pe_dev_traverse(pe, eeh_report_resume, NULL);
- return;
+ return false;
excess_failures:
/*
@@ -915,8 +915,12 @@ perm_error:
pci_lock_rescan_remove();
pci_hp_remove_devices(frozen_bus);
pci_unlock_rescan_remove();
+
+ /* The passed PE should no longer be used */
+ return true;
}
}
+ return false;
}
static void eeh_handle_special_event(void)
@@ -982,7 +986,14 @@ static void eeh_handle_special_event(void)
*/
if (rc == EEH_NEXT_ERR_FROZEN_PE ||
rc == EEH_NEXT_ERR_FENCED_PHB) {
- eeh_handle_normal_event(pe);
+ /*
+ * eeh_handle_normal_event() can make the PE stale if it
+ * determines that the PE cannot possibly be recovered.
+ * Don't modify the PE state if that's the case.
+ */
+ if (eeh_handle_normal_event(pe))
+ continue;
+
eeh_pe_state_clear(pe, EEH_PE_RECOVERING);
} else {
pci_lock_rescan_remove();