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tracing: Fix a kmemleak false positive in tracing_map
[ Upstream commit f25667e598
]
Doing the command:
echo 'hist:key=common_pid.execname,common_timestamp' > /sys/kernel/debug/tracing/events/xxx/trigger
Triggers many kmemleak reports:
unreferenced object 0xffff0000c7ea4980 (size 128):
comm "bash", pid 338, jiffies 4294912626 (age 9339.324s)
hex dump (first 32 bytes):
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<00000000f3469921>] kmem_cache_alloc_trace+0x4c0/0x6f0
[<0000000054ca40c3>] hist_trigger_elt_data_alloc+0x140/0x178
[<00000000633bd154>] tracing_map_init+0x1f8/0x268
[<000000007e814ab9>] event_hist_trigger_func+0xca0/0x1ad0
[<00000000bf8520ed>] trigger_process_regex+0xd4/0x128
[<00000000f549355a>] event_trigger_write+0x7c/0x120
[<00000000b80f898d>] vfs_write+0xc4/0x380
[<00000000823e1055>] ksys_write+0x74/0xf8
[<000000008a9374aa>] __arm64_sys_write+0x24/0x30
[<0000000087124017>] do_el0_svc+0x88/0x1c0
[<00000000efd0dcd1>] el0_svc+0x1c/0x28
[<00000000dbfba9b3>] el0_sync_handler+0x88/0xc0
[<00000000e7399680>] el0_sync+0x148/0x180
unreferenced object 0xffff0000c7ea4980 (size 128):
comm "bash", pid 338, jiffies 4294912626 (age 9339.324s)
hex dump (first 32 bytes):
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<00000000f3469921>] kmem_cache_alloc_trace+0x4c0/0x6f0
[<0000000054ca40c3>] hist_trigger_elt_data_alloc+0x140/0x178
[<00000000633bd154>] tracing_map_init+0x1f8/0x268
[<000000007e814ab9>] event_hist_trigger_func+0xca0/0x1ad0
[<00000000bf8520ed>] trigger_process_regex+0xd4/0x128
[<00000000f549355a>] event_trigger_write+0x7c/0x120
[<00000000b80f898d>] vfs_write+0xc4/0x380
[<00000000823e1055>] ksys_write+0x74/0xf8
[<000000008a9374aa>] __arm64_sys_write+0x24/0x30
[<0000000087124017>] do_el0_svc+0x88/0x1c0
[<00000000efd0dcd1>] el0_svc+0x1c/0x28
[<00000000dbfba9b3>] el0_sync_handler+0x88/0xc0
[<00000000e7399680>] el0_sync+0x148/0x180
The reason is elts->pages[i] is alloced by get_zeroed_page.
and kmemleak will not scan the area alloced by get_zeroed_page.
The address stored in elts->pages will be regarded as leaked.
That is, the elts->pages[i] will have pointers loaded onto it as well, and
without telling kmemleak about it, those pointers will look like memory
without a reference.
To fix this, call kmemleak_alloc to tell kmemleak to scan elts->pages[i]
Link: https://lkml.kernel.org/r/20211124140801.87121-1-chenjun102@huawei.com
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
parent
43b145f3a2
commit
9985d29c47
1 changed files with 3 additions and 0 deletions
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@ -15,6 +15,7 @@
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#include <linux/jhash.h>
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#include <linux/slab.h>
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#include <linux/sort.h>
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#include <linux/kmemleak.h>
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#include "tracing_map.h"
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#include "trace.h"
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@ -307,6 +308,7 @@ static void tracing_map_array_free(struct tracing_map_array *a)
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for (i = 0; i < a->n_pages; i++) {
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if (!a->pages[i])
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break;
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kmemleak_free(a->pages[i]);
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free_page((unsigned long)a->pages[i]);
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}
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@ -342,6 +344,7 @@ static struct tracing_map_array *tracing_map_array_alloc(unsigned int n_elts,
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a->pages[i] = (void *)get_zeroed_page(GFP_KERNEL);
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if (!a->pages[i])
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goto free;
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kmemleak_alloc(a->pages[i], PAGE_SIZE, 1, GFP_KERNEL);
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}
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out:
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return a;
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