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| 1 | +From 7ca88764d45c209791e8813131c1457c2e9e51e7 Mon Sep 17 00:00:00 2001 |
| 2 | +From: Yevgeny Pats < [email protected]> |
| 3 | +Date: Mon, 11 Jan 2016 12:05:28 +0000 |
| 4 | +Subject: KEYS: Fix keyring ref leak in join_session_keyring() |
| 5 | + |
| 6 | +If a thread is asked to join as a session keyring the keyring that's already |
| 7 | +set as its session, we leak a keyring reference. |
| 8 | + |
| 9 | +This can be tested with the following program: |
| 10 | + |
| 11 | + #include <stddef.h> |
| 12 | + #include <stdio.h> |
| 13 | + #include <sys/types.h> |
| 14 | + #include <keyutils.h> |
| 15 | + |
| 16 | + int main(int argc, const char *argv[]) |
| 17 | + { |
| 18 | + int i = 0; |
| 19 | + key_serial_t serial; |
| 20 | + |
| 21 | + serial = keyctl(KEYCTL_JOIN_SESSION_KEYRING, |
| 22 | + "leaked-keyring"); |
| 23 | + if (serial < 0) { |
| 24 | + perror("keyctl"); |
| 25 | + return -1; |
| 26 | + } |
| 27 | + |
| 28 | + if (keyctl(KEYCTL_SETPERM, serial, |
| 29 | + KEY_POS_ALL | KEY_USR_ALL) < 0) { |
| 30 | + perror("keyctl"); |
| 31 | + return -1; |
| 32 | + } |
| 33 | + |
| 34 | + for (i = 0; i < 100; i++) { |
| 35 | + serial = keyctl(KEYCTL_JOIN_SESSION_KEYRING, |
| 36 | + "leaked-keyring"); |
| 37 | + if (serial < 0) { |
| 38 | + perror("keyctl"); |
| 39 | + return -1; |
| 40 | + } |
| 41 | + } |
| 42 | + |
| 43 | + return 0; |
| 44 | + } |
| 45 | + |
| 46 | +If, after the program has run, there something like the following line in |
| 47 | +/proc/keys: |
| 48 | + |
| 49 | +3f3d898f I--Q--- 100 perm 3f3f0000 0 0 keyring leaked-keyring: empty |
| 50 | + |
| 51 | +with a usage count of 100 * the number of times the program has been run, |
| 52 | +then the kernel is malfunctioning. If leaked-keyring has zero usages or |
| 53 | +has been garbage collected, then the problem is fixed. |
| 54 | + |
| 55 | +Reported-by: Yevgeny Pats < [email protected]> |
| 56 | +Signed-off-by: David Howells < [email protected]> |
| 57 | +--- |
| 58 | + security/keys/process_keys.c | 1 + |
| 59 | + 1 file changed, 1 insertion(+) |
| 60 | + |
| 61 | +diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c |
| 62 | +index a3f85d2..e6d50172 100644 |
| 63 | +--- a/security/keys/process_keys.c |
| 64 | ++++ b/security/keys/process_keys.c |
| 65 | +@@ -794,6 +794,7 @@ long join_session_keyring(const char *name) |
| 66 | + ret = PTR_ERR(keyring); |
| 67 | + goto error2; |
| 68 | + } else if (keyring == new->session_keyring) { |
| 69 | ++ key_put(keyring); |
| 70 | + ret = 0; |
| 71 | + goto error2; |
| 72 | + } |
| 73 | +-- |
| 74 | +2.7.0.rc3 |
| 75 | + |
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