| Message ID | 1531782831-1186-1-git-send-email-mathieu.poirier@linaro.org |
|---|---|
| State | Accepted |
| Commit | 7f635ff187ab6be0b350b3ec06791e376af238ab |
| Headers | show |
| Series | perf/core: Fix crash when using HW tracing kernel filters | expand |
diff --git a/kernel/events/core.c b/kernel/events/core.c index 8f0434a9951a..a56f10b1e13b 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7335,6 +7335,10 @@ static bool perf_addr_filter_match(struct perf_addr_filter *filter, struct file *file, unsigned long offset, unsigned long size) { + /* d_inode(NULL) won't be equal to any mapped user space file */ + if (!filter->path.dentry) + return false; + if (d_inode(filter->path.dentry) != file_inode(file)) return false;
In function perf_event_parse_addr_filter(), the path::dentry of each struct perf_addr_filter is left unassigned (as it should be) when the pattern being parsed is related to kernel space. But in function perf_addr_filter_match() the same dentry'ies are given to d_inode() where the value is not expected to be NULL, resulting in the following splat: [ 53.451557] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000058 [ 53.460368] Mem abort info: [ 53.463134] ESR = 0x96000004 [ 53.466158] Exception class = DABT (current EL), IL = 32 bits [ 53.472019] SET = 0, FnV = 0 [ 53.475042] EA = 0, S1PTW = 0 [ 53.478150] Data abort info: [ 53.481000] ISV = 0, ISS = 0x00000004 [ 53.484796] CM = 0, WnR = 0 [ 53.487734] user pgtable: 4k pages, 48-bit VAs, pgdp = 00000000f0644b81 [ 53.494283] [0000000000000058] pgd=0000000000000000 [ 53.499181] Internal error: Oops: 96000004 [#1] PREEMPT SMP [ 53.504697] Modules linked in: [ 53.507726] CPU: 2 PID: 2860 Comm: uname Not tainted 4.18.0-rc5-dirty #288 [ 53.514531] Hardware name: ARM Juno development board (r0) (DT) [ 53.520392] pstate: 20000085 (nzCv daIf -PAN -UAO) [ 53.525141] pc : perf_event_mmap+0x2fc/0x5a0 [ 53.529368] lr : perf_event_mmap+0x2c8/0x5a0 [ 53.533593] sp : ffff000010883a10 [ 53.536872] x29: ffff000010883a10 x28: ffff8009749126c0 [ 53.542137] x27: 0000000000000000 x26: ffff800971221000 [ 53.547401] x25: ffff80097678bef0 x24: ffff0000091cb000 [ 53.552665] x23: ffff800971221430 x22: ffff80097100fe00 [ 53.557930] x21: 0000000000001078 x20: ffff0000091af000 [ 53.563194] x19: ffff800971221420 x18: 0000000000006451 [ 53.568457] x17: 000000000000644f x16: ffff000009404790 [ 53.573721] x15: ffff00000932c3b0 x14: 000000000000644e [ 53.578985] x13: 00000000ed3bb5ef x12: ffff8009711e1de8 [ 53.584248] x11: 0000000000000000 x10: ffff0000091af808 [ 53.589512] x9 : ffff0000091ea000 x8 : ffff0000091af808 [ 53.594776] x7 : 0000000000000002 x6 : ffff8009740c7540 [ 53.600040] x5 : 0000000000000000 x4 : 00000000000067e8 [ 53.605303] x3 : 0000000000000000 x2 : ffff800971131800 [ 53.610567] x1 : 0000000000000002 x0 : 0000000000000000 [ 53.615832] Process uname (pid: 2860, stack limit = 0x000000001cbcca37) [ 53.622378] Call trace: [ 53.624798] perf_event_mmap+0x2fc/0x5a0 [ 53.628683] mmap_region+0x124/0x570 [ 53.632221] do_mmap+0x344/0x4f8 [ 53.635414] vm_mmap_pgoff+0xe4/0x110 [ 53.639037] vm_mmap+0x2c/0x40 [ 53.642061] elf_map+0x60/0x108 [ 53.645169] load_elf_binary+0x450/0x12c4 [ 53.649138] search_binary_handler+0x90/0x290 [ 53.653449] __do_execve_file.isra.13+0x6e4/0x858 [ 53.658104] sys_execve+0x3c/0x50 [ 53.661385] el0_svc_naked+0x30/0x34 [ 53.664924] Code: eb02027f 54000300 f9400c45 f94012c6 (f9402ca5) [ 53.670959] ---[ end trace 3ef799e7226990e4 ]--- This patch is fixing the problem by introducing a new check in function perf_addr_filter_match() to see if the filter's dentry is NULL. Fixes: 9511bce9fe8e ("perf/core: Fix bad use of igrab()") Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org> --- kernel/events/core.c | 4 ++++ 1 file changed, 4 insertions(+) -- 2.7.4