From: Mathieu Poirier <[email protected]> commit 7f635ff187ab6be0b350b3ec06791e376af238ab upstream
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 dentries are given to d_inode() where the value is not expected to be NULL, resulting in the following splat: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000058 pc : perf_event_mmap+0x2fc/0x5a0 lr : perf_event_mmap+0x2c8/0x5a0 Process uname (pid: 2860, stack limit = 0x000000001cbcca37) Call trace: perf_event_mmap+0x2fc/0x5a0 mmap_region+0x124/0x570 do_mmap+0x344/0x4f8 vm_mmap_pgoff+0xe4/0x110 vm_mmap+0x2c/0x40 elf_map+0x60/0x108 load_elf_binary+0x450/0x12c4 search_binary_handler+0x90/0x290 __do_execve_file.isra.13+0x6e4/0x858 sys_execve+0x3c/0x50 el0_svc_naked+0x30/0x34 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. Signed-off-by: Mathieu Poirier <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Acked-by: Alexander Shishkin <[email protected]> Cc: Arnaldo Carvalho de Melo <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Stephane Eranian <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Vince Weaver <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Fixes: 9511bce9fe8e ("perf/core: Fix bad use of igrab()") Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> Signed-off-by: Sudip Mukherjee <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- kernel/events/core.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7124,6 +7124,10 @@ static bool perf_addr_filter_match(struc 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;
