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authorElliott Hughes <enh@google.com>2018-02-09 06:41:52 (GMT)
committerRob Landley <rob@landley.net>2018-02-09 19:06:58 (GMT)
commit2530d54f1145a7bf6b634f630344ed42adf388e5 (patch)
treeb93d3f6b30f74ec08ddc93de23f41b1e4bc63538
parent912646fc08d1b5e497f5ddb9b14e994f6b44e291 (diff)
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Fix the pidof comm and cmdline tests.
If we have a 15-byte name, we don't know whether comm actually matches or is a truncated form of a longer name that has a common prefix. For example, with "this-is-a-very-long-name-that-is-too-long", we shouldn't match "this-is-a-very-" (but the old code would). The cmdline code was also broken on Android because it used basename(3) rather than getbasename. This doesn't affect glibc because there's a workaround in portability.h to ensure that we get the non-POSIX basename(3) with glibc but then a non-glibc section that ensures everyone else gets POSIX basename(3). That should probably be removed (and maybe `basename` poisoned) to prevent similar mistakes in future. Bug: http://b/73123244
-rw-r--r--lib/lib.c18
1 files changed, 9 insertions, 9 deletions
diff --git a/lib/lib.c b/lib/lib.c
index 7f5fbbd..e5c9479 100644
--- a/lib/lib.c
+++ b/lib/lib.c
@@ -1036,13 +1036,13 @@ void names_to_pid(char **names, int (*callback)(pid_t pid, char *name))
for (cur = names; *cur; cur++) {
struct stat st1, st2;
- char *bb = basename(*cur);
- off_t len;
+ char *bb = getbasename(*cur);
+ off_t len = strlen(bb);
- // fast path: only matching a filename (no path) that fits in comm
- if (strncmp(comm, bb, 15)) continue;
- len = strlen(bb);
- if (bb==*cur && len<16) goto match;
+ // Fast path: only matching a filename (no path) that fits in comm.
+ // `len` must be 14 or less because with a full 15 bytes we don't
+ // know whether the name fit or was truncated.
+ if (len<=14 && bb==*cur && !strcmp(comm, bb)) goto match;
// If we have a path to existing file only match if same inode
if (bb!=*cur && !stat(*cur, &st1)) {
@@ -1059,12 +1059,12 @@ void names_to_pid(char **names, int (*callback)(pid_t pid, char *name))
sprintf(cmd = libbuf+16, "/proc/%u/cmdline", u);
len = sizeof(libbuf)-17;
if (!(cmd = readfileat(AT_FDCWD, cmd, cmd, &len))) continue;
- // readfile only guarnatees one null terminator and we need two
+ // readfile only guarantees one null terminator and we need two
// (yes the kernel should do this for us, don't care)
cmd[len] = 0;
}
- if (!strcmp(bb, basename(cmd))) goto match;
- if (bb!=*cur && !strcmp(bb, basename(cmd+strlen(cmd)+1))) goto match;
+ if (!strcmp(bb, getbasename(cmd))) goto match;
+ if (bb!=*cur && !strcmp(bb, getbasename(cmd+strlen(cmd)+1))) goto match;
continue;
match:
if (callback(u, *cur)) break;