diff options
| author | Kajol Jain <kjain@linux.ibm.com> | 2022-05-05 21:04:51 +0530 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2022-05-06 12:44:03 +1000 |
| commit | 348c71344111d7a48892e3e52264ff11956fc196 (patch) | |
| tree | 7b6e73fde4dfc3729d5eaf1757ef8fb62e7fdba4 | |
| parent | 6d65028eb67dbb7627651adfc460d64196d38bd8 (diff) | |
| download | linux-348c71344111d7a48892e3e52264ff11956fc196.tar.bz2 | |
powerpc/papr_scm: Fix buffer overflow issue with CONFIG_FORTIFY_SOURCE
With CONFIG_FORTIFY_SOURCE enabled, string functions will also perform
dynamic checks for string size which can panic the kernel, like incase
of overflow detection.
In papr_scm, papr_scm_pmu_check_events function uses stat->stat_id with
string operations, to populate the nvdimm_events_map array. Since
stat_id variable is not NULL terminated, the kernel panics with
CONFIG_FORTIFY_SOURCE enabled at boot time.
Below are the logs of kernel panic:
detected buffer overflow in __fortify_strlen
------------[ cut here ]------------
kernel BUG at lib/string_helpers.c:980!
Oops: Exception in kernel mode, sig: 5 [#1]
NIP [c00000000077dad0] fortify_panic+0x28/0x38
LR [c00000000077dacc] fortify_panic+0x24/0x38
Call Trace:
[c0000022d77836e0] [c00000000077dacc] fortify_panic+0x24/0x38 (unreliable)
[c00800000deb2660] papr_scm_pmu_check_events.constprop.0+0x118/0x220 [papr_scm]
[c00800000deb2cb0] papr_scm_probe+0x288/0x62c [papr_scm]
[c0000000009b46a8] platform_probe+0x98/0x150
Fix this issue by using kmemdup_nul() to copy the content of
stat->stat_id directly to the nvdimm_events_map array.
mpe: stat->stat_id comes from the hypervisor, not userspace, so there is
no security exposure.
Fixes: 4c08d4bbc089 ("powerpc/papr_scm: Add perf interface support")
Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220505153451.35503-1-kjain@linux.ibm.com
| -rw-r--r-- | arch/powerpc/platforms/pseries/papr_scm.c | 7 |
1 files changed, 2 insertions, 5 deletions
diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c index f58728d5f10d..39962c905542 100644 --- a/arch/powerpc/platforms/pseries/papr_scm.c +++ b/arch/powerpc/platforms/pseries/papr_scm.c @@ -462,7 +462,6 @@ static int papr_scm_pmu_check_events(struct papr_scm_priv *p, struct nvdimm_pmu { struct papr_scm_perf_stat *stat; struct papr_scm_perf_stats *stats; - char *statid; int index, rc, count; u32 available_events; @@ -493,14 +492,12 @@ static int papr_scm_pmu_check_events(struct papr_scm_priv *p, struct nvdimm_pmu for (index = 0, stat = stats->scm_statistic, count = 0; index < available_events; index++, ++stat) { - statid = kzalloc(strlen(stat->stat_id) + 1, GFP_KERNEL); - if (!statid) { + p->nvdimm_events_map[count] = kmemdup_nul(stat->stat_id, 8, GFP_KERNEL); + if (!p->nvdimm_events_map[count]) { rc = -ENOMEM; goto out_nvdimm_events_map; } - strcpy(statid, stat->stat_id); - p->nvdimm_events_map[count] = statid; count++; } p->nvdimm_events_map[count] = NULL; |