diff options
author | Russell Currey <ruscur@russell.cc> | 2017-04-19 17:39:26 +1000 |
---|---|---|
committer | Ben Hutchings <ben@decadent.org.uk> | 2017-08-26 02:14:44 +0100 |
commit | f40caa4da17aaf347e941078c0f6cdc60f04e6e1 (patch) | |
tree | 2e5fd98f9b0f985cdd2a8495506ff6f459e4e6af /arch | |
parent | 7d7bf9b4595a195f00f022102f9dc88fd32b84d9 (diff) | |
download | linux-stable-f40caa4da17aaf347e941078c0f6cdc60f04e6e1.tar.gz linux-stable-f40caa4da17aaf347e941078c0f6cdc60f04e6e1.tar.bz2 linux-stable-f40caa4da17aaf347e941078c0f6cdc60f04e6e1.zip |
powerpc/eeh: Avoid use after free in eeh_handle_special_event()
commit daeba2956f32f91f3493788ff6ee02fb1b2f02fa upstream.
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")
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>
[bwh: Backported to 3.16: adjust context, indentation]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/powerpc/kernel/eeh_driver.c | 19 |
1 files changed, 15 insertions, 4 deletions
diff --git a/arch/powerpc/kernel/eeh_driver.c b/arch/powerpc/kernel/eeh_driver.c index e25ee5de2f6f..0e3ad5591414 100644 --- a/arch/powerpc/kernel/eeh_driver.c +++ b/arch/powerpc/kernel/eeh_driver.c @@ -584,7 +584,7 @@ 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; int rc = 0; @@ -594,7 +594,7 @@ static void eeh_handle_normal_event(struct eeh_pe *pe) if (!frozen_bus) { pr_err("%s: Cannot find PCI bus for PHB#%d-PE#%x\n", __func__, pe->phb->global_number, pe->addr); - return; + return false; } eeh_pe_update_time_stamp(pe); @@ -711,7 +711,7 @@ 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: /* @@ -751,7 +751,11 @@ perm_error: pci_lock_rescan_remove(); pcibios_remove_pci_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) @@ -817,7 +821,14 @@ 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(); |