All of
 help / color / mirror / Atom feed
From: Imran Khan <>
Subject: [RFC PATCH 1/2] lib, stackdepot: check stackdepot handle before accessing slabs.
Date: Wed,  1 Sep 2021 15:19:13 +1000	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

stack_depot_save allocates slabs that will be used for storing
objects in future.If this slab allocation fails we may get to
a situation where space allocation for a new stack_record fails,
causing stack_depot_save to return 0 as handle.
If user of this handle ends up invoking stack_depot_fetch with
this handle value, current implementation of stack_depot_fetch
will end up using slab from wrong index.
To avoid this check handle value at the beginning.
Also issue a warning for nil handle values and when slab allocation
for stackdepot fails for the first time.

Signed-off-by: Imran Khan <>
Suggested-by: Vlastimil Babka <>
 lib/stackdepot.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lib/stackdepot.c b/lib/stackdepot.c
index 0a2e417f83cb..1d42ef9ef766 100644
--- a/lib/stackdepot.c
+++ b/lib/stackdepot.c
@@ -232,6 +232,10 @@ unsigned int stack_depot_fetch(depot_stack_handle_t handle,
 	struct stack_record *stack;
 	*entries = NULL;
+	if (!handle) {
+		WARN(1, "stack depot handle is absent.\n");
+		return 0;
+	}
 	if (parts.slabindex > depot_index) {
 		WARN(1, "slab index %d out of bounds (%d) for stack id %08x\n",
 			parts.slabindex, depot_index, handle);
@@ -303,6 +307,8 @@ depot_stack_handle_t stack_depot_save(unsigned long *entries,
 		page = alloc_pages(alloc_flags, STACK_ALLOC_ORDER);
 		if (page)
 			prealloc = page_address(page);
+		else
+			WARN_ONCE(1, "slab allocation for stack depot failed.\n");
 	raw_spin_lock_irqsave(&depot_lock, flags);

  reply	other threads:[~2021-09-01  5:19 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-01  5:19 [RFC PATCH 0/2] lib, stackdepot: check stackdepot handle before accessing slabs Imran Khan
2021-09-01  5:19 ` Imran Khan [this message]
2021-09-01  8:58   ` [RFC PATCH 1/2] " Vlastimil Babka
2021-09-02  0:12     ` imran.f.khan
2021-09-01  5:19 ` [RFC PATCH 2/2] lib, stackdepot: Add helper to print stack entries Imran Khan
2021-09-01  9:07   ` Vlastimil Babka
2021-09-02  0:11     ` imran.f.khan
2021-09-02  8:00       ` Vlastimil Babka

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.