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authorBaokun Li <libaokun1@huawei.com>2021-11-15 09:31:42 +0800
committerRichard Weinberger <richard@nod.at>2021-12-23 22:23:58 +0100
commit88618feecf44e774e03cf49872567398b0177d25 (patch)
tree987e80ac90efa6db26c5191001fbab3b6e1a640b /fs/ubifs
parentd3de970bcba0fb171e6aceaa0723d2cd842dc25c (diff)
ubifs: fix slab-out-of-bounds in ubifs_change_lp
Hulk Robot reported a KASAN report about slab-out-of-bounds: ================================================================== BUG: KASAN: slab-out-of-bounds in ubifs_change_lp+0x3a9/0x1390 [ubifs] Read of size 8 at addr ffff888101c961f8 by task fsstress/1068 [...] Call Trace: check_memory_region+0x1c1/0x1e0 ubifs_change_lp+0x3a9/0x1390 [ubifs] ubifs_change_one_lp+0x170/0x220 [ubifs] ubifs_garbage_collect+0x7f9/0xda0 [ubifs] ubifs_budget_space+0xfe4/0x1bd0 [ubifs] ubifs_write_begin+0x528/0x10c0 [ubifs] Allocated by task 1068: kmemdup+0x25/0x50 ubifs_lpt_lookup_dirty+0x372/0xb00 [ubifs] ubifs_update_one_lp+0x46/0x260 [ubifs] ubifs_tnc_end_commit+0x98b/0x1720 [ubifs] do_commit+0x6cb/0x1950 [ubifs] ubifs_run_commit+0x15a/0x2b0 [ubifs] ubifs_budget_space+0x1061/0x1bd0 [ubifs] ubifs_write_begin+0x528/0x10c0 [ubifs] [...] ================================================================== In ubifs_garbage_collect(), if ubifs_find_dirty_leb returns an error, lp is an uninitialized variable. But lp.num might be used in the out branch, which is a random value. If the value is -1 or another value that can pass the check, soob may occur in the ubifs_change_lp() in the following procedure. To solve this problem, we initialize lp.lnum to -1, and then initialize it correctly in ubifs_find_dirty_leb, which is not equal to -1, and ubifs_return_leb is executed only when lp.lnum != -1. if find a retained or indexing LEB and continue to next loop, but break before find another LEB, the "taken" flag of this LEB will be cleaned in ubi_return_lebi(). This bug has also been fixed in this patch. Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Baokun Li <libaokun1@huawei.com> Signed-off-by: Richard Weinberger <richard@nod.at>
Diffstat (limited to 'fs/ubifs')
-rw-r--r--fs/ubifs/gc.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/fs/ubifs/gc.c b/fs/ubifs/gc.c
index dc3e26e9ed7b..05e1eeae8457 100644
--- a/fs/ubifs/gc.c
+++ b/fs/ubifs/gc.c
@@ -692,6 +692,9 @@ int ubifs_garbage_collect(struct ubifs_info *c, int anyway)
for (i = 0; ; i++) {
int space_before, space_after;
+ /* Maybe continue after find and break before find */
+ lp.lnum = -1;
+
cond_resched();
/* Give the commit an opportunity to run */
@@ -843,7 +846,8 @@ out:
ubifs_wbuf_sync_nolock(wbuf);
ubifs_ro_mode(c, ret);
mutex_unlock(&wbuf->io_mutex);
- ubifs_return_leb(c, lp.lnum);
+ if (lp.lnum != -1)
+ ubifs_return_leb(c, lp.lnum);
return ret;
}