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author | 2012-09-23 08:18:06 +0800 | |
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committer | 2012-09-23 14:45:26 -0700 | |
commit | ef6e7816b4546475d04b4ea22d58c48472157c70 (patch) | |
tree | 6589164940cf4a0f113b1f48dbcce60391112c4e | |
parent | Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus (diff) | |
download | linux-ef6e7816b4546475d04b4ea22d58c48472157c70.tar.gz linux-ef6e7816b4546475d04b4ea22d58c48472157c70.tar.bz2 linux-ef6e7816b4546475d04b4ea22d58c48472157c70.zip |
edac_mc: fix messy kfree calls in the error path
coccinelle warns about:
+ drivers/edac/edac_mc.c:429:9-23: ERROR: reference preceded by free on line 429
421 if (mci->csrows) {
> 422 for (chn = 0; chn < tot_channels; chn++) {
423 csr = mci->csrows[chn];
424 if (csr) {
> 425 for (chn = 0; chn < tot_channels; chn++)
426 kfree(csr->channels[chn]);
427 kfree(csr);
428 }
> 429 kfree(mci->csrows[i]);
430 }
431 kfree(mci->csrows);
432 }
and that code block seem to mess things up in several ways (double free, memory
leak, out-of-bound reads etc.):
L422: The iterator "chn" and bound "tot_channels" are totally wrong. Should be
"row" and "tot_csrows" respectively. Which means either memory leak, or
out-of-bound reads (which if does not trigger an immediate page fault
error, will further lead to kfree() on random addresses).
L425: The inner loop is reusing the same iterator "chn" as the outer loop,
which could lead to premature end of the outer loop, and hence memory leak.
L429: The array index 'i' in mci->csrows[i] is a temporary value used in
previous loops, and won't change at all in the current loop. Which
means either out-of-bound read and possibly kfree(random number), or the
same mci->csrows[i] get freed once and again, and possibly double free
for the kfree(csr) in L427.
L426/L427: a kfree(csr->channels) is needed in between to avoid leaking the memory.
The buggy code was introduced by commit de3910eb ("edac: change the mem
allocation scheme to make Documentation/kobject.txt happy") in the 3.6-rc1
merge window. Fix it by freeing up resources in this order:
free csrows[i]->channels[j]
free csrows[i]->channels
free csrows[i]
free csrows
CC: Mauro Carvalho Chehab <mchehab@redhat.com>
CC: Shaun Ruffell <sruffell@digium.com>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r-- | drivers/edac/edac_mc.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c index 616d90bcb3a4..9037ffa100d5 100644 --- a/drivers/edac/edac_mc.c +++ b/drivers/edac/edac_mc.c @@ -419,14 +419,16 @@ error: kfree(mci->dimms); } if (mci->csrows) { - for (chn = 0; chn < tot_channels; chn++) { - csr = mci->csrows[chn]; + for (row = 0; row < tot_csrows; row++) { + csr = mci->csrows[row]; if (csr) { - for (chn = 0; chn < tot_channels; chn++) - kfree(csr->channels[chn]); + if (csr->channels) { + for (chn = 0; chn < tot_channels; chn++) + kfree(csr->channels[chn]); + kfree(csr->channels); + } kfree(csr); } - kfree(mci->csrows[i]); } kfree(mci->csrows); } |