When a task used prctl(PR_SET_MM, PR_SET_MM_ARG_{START,END}, ...)
(e.g. the systemd's child "(sd-pam)" in Fedora), the "ps -a" option
could fail with "ps: cannot allocate any more memory!".
# ./crash -d 1
...
crash> ps -a 1591
...
PID: 1591 TASK: ffff9c7077d7b1c0 CPU: 1 COMMAND: "(sd-pam)"
arg_start: 7f2f544de000 arg_end: 7f2f544de009 (9)
env_start: 7ffcff12af88 env_end: 7ffcff12afdf (87)
...
smallest: 16
largest: 883333320672
embedded: 2
max_embedded: 3
mallocs: 22
frees: 22
reqs/total: 912/1766672402731
average size: 1937140792
ps: cannot allocate any more memory!
This happens because it assumes that the ranges of arg and env are
contiguous.
buf = GETBUF(env_end - arg_start + 1);
This patch devides the GETBUF() into two times for arg and env.
Signed-off-by: Kazuhito Hagio <k-hagio@xxxxxxxxxxxxx>
---
task.c | 94 +++++++++++++++++++++++++++++++++++++-----------------------------
1 file changed, 53 insertions(+), 41 deletions(-)
diff --git a/task.c b/task.c
index 2418e4c..55242c5 100644
--- a/task.c
+++ b/task.c
@@ -3865,6 +3865,44 @@ show_milliseconds(struct task_context *tc, struct psinfo *psi)
}
}
+static char *
+read_arg_string(struct task_context *tc, char *buf, ulong start, ulong end)
+{
+ physaddr_t paddr;
+ ulong uvaddr, size, cnt;
+ char *bufptr;
+
+ uvaddr = start;
+ size = end - start;
+ bufptr = buf;
+
+ while (size > 0) {
+ if (!uvtop(tc, uvaddr, &paddr, 0)) {
+ error(INFO, "cannot access user stack address: %lx\n\n",
+ uvaddr);
+ return NULL;
+ }
+
+ cnt = PAGESIZE() - PAGEOFFSET(uvaddr);
+
+ if (cnt > size)
+ cnt = size;
+
+ if (!readmem(paddr, PHYSADDR, bufptr, cnt,
+ "user stack contents", RETURN_ON_ERROR|QUIET)) {
+ error(INFO, "cannot access user stack address: %lx\n\n",
+ uvaddr);
+ return NULL;
+ }
+
+ uvaddr += cnt;
+ bufptr += cnt;
+ size -= cnt;
+ }
+
+ return bufptr;
+}
+
/*
* Show the argv and envp strings pointed to by mm_struct->arg_start
* and mm_struct->env_start. The user addresses need to broken up
@@ -3875,10 +3913,7 @@ static void
show_task_args(struct task_context *tc)
{
ulong arg_start, arg_end, env_start, env_end;
- char *buf, *bufptr, *p1;
- char *as, *ae, *es, *ee;
- physaddr_t paddr;
- ulong uvaddr, size, cnt;
+ char *buf, *p1, *end;
int c, d;
print_task_header(fp, tc, 0);
@@ -3910,43 +3945,13 @@ show_task_args(struct task_context *tc)
env_start, env_end, env_end - env_start);
}
- buf = GETBUF(env_end - arg_start + 1);
-
- uvaddr = arg_start;
- size = env_end - arg_start;
- bufptr = buf;
-
- while (size > 0) {
- if (!uvtop(tc, uvaddr, &paddr, 0)) {
- error(INFO, "cannot access user stack address: %lx\n\n",
- uvaddr);
- goto bailout;
- }
-
- cnt = PAGESIZE() - PAGEOFFSET(uvaddr);
-
- if (cnt > size)
- cnt = size;
-
- if (!readmem(paddr, PHYSADDR, bufptr, cnt,
- "user stack contents", RETURN_ON_ERROR|QUIET)) {
- error(INFO, "cannot access user stack address: %lx\n\n",
- uvaddr);
- goto bailout;
- }
-
- uvaddr += cnt;
- bufptr += cnt;
- size -= cnt;
- }
-
- as = buf;
- ae = &buf[arg_end - arg_start];
- es = &buf[env_start - arg_start];
- ee = &buf[env_end - arg_start];
+ buf = GETBUF(arg_end - arg_start + 1);
+ end = read_arg_string(tc, buf, arg_start, arg_end);
+ if (!end)
+ goto bailout;
fprintf(fp, "ARG: ");
- for (p1 = as, c = 0; p1 < ae; p1++) {
+ for (p1 = buf, c = 0; p1 < end; p1++) {
if (*p1 == NULLCHAR) {
if (c)
fprintf(fp, " ");
@@ -3957,14 +3962,21 @@ show_task_args(struct task_context *tc)
}
}
+ FREEBUF(buf);
+
+ buf = GETBUF(env_end - env_start + 1);
+ end = read_arg_string(tc, buf, env_start, env_end);
+ if (!end)
+ goto bailout;
+
fprintf(fp, "\nENV: ");
- for (p1 = es, c = d = 0; p1 < ee; p1++) {
+ for (p1 = buf, c = d = 0; p1 < end; p1++) {
if (*p1 == NULLCHAR) {
if (c)
fprintf(fp, "\n");
c = 0;
} else {
- fprintf(fp, "%s%c", !c && (p1 != es) ? " " : "", *p1);
+ fprintf(fp, "%s%c", !c && (p1 != buf) ? " " : "", *p1);
c++, d++;
}
}
--
1.8.3.1
--
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