If an extent has e_len set to zero, the kernel will oops with a
BUG_ON. Unfortuntaely, e2fsck wasn't catching this case. The kernel
needs to be fixed to notice this case and call ext4_error() instead of
failing an assertion check, but e2fsck should catch this case and
repair it (by deleting the errant extent).
Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
---
e2fsck/pass1.c | 2 ++
e2fsck/problem.c | 5 +++++
e2fsck/problem.h | 3 +++
tests/f_ext_zero_len/expect.1 | 13 +++++++++++++
tests/f_ext_zero_len/expect.2 | 7 +++++++
tests/f_ext_zero_len/image.gz | Bin 0 -> 576 bytes
tests/f_ext_zero_len/name | 1 +
7 files changed, 31 insertions(+), 0 deletions(-)
create mode 100644 tests/f_ext_zero_len/expect.1
create mode 100644 tests/f_ext_zero_len/expect.2
create mode 100644 tests/f_ext_zero_len/image.gz
create mode 100644 tests/f_ext_zero_len/name
diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c
index 5faa093..9f4142b 100644
--- a/e2fsck/pass1.c
+++ b/e2fsck/pass1.c
@@ -1778,6 +1778,8 @@ static void scan_extent_node(e2fsck_t ctx, struct problem_context *pctx,
problem = PR_1_EXTENT_BAD_START_BLK;
else if (extent.e_lblk < start_block)
problem = PR_1_OUT_OF_ORDER_EXTENTS;
+ else if (extent.e_len == 0)
+ problem = PR_1_EXTENT_LENGTH_ZERO;
else if (is_leaf &&
(extent.e_pblk + extent.e_len) >
ext2fs_blocks_count(ctx->fs->super))
diff --git a/e2fsck/problem.c b/e2fsck/problem.c
index 579c838..b951eb7 100644
--- a/e2fsck/problem.c
+++ b/e2fsck/problem.c
@@ -936,6 +936,11 @@ static struct e2fsck_problem problem_table[] = {
N_("The bad @b @i looks @n. "),
PROMPT_CLEAR, 0 },
+ /* Extent has zero length */
+ { PR_1_EXTENT_LENGTH_ZERO,
+ N_("@i %i has zero length extent\n\t(@n logical @b %c, physical @b %b)\n"),
+ PROMPT_CLEAR, 0 },
+
/* Pass 1b errors */
/* Pass 1B: Rescan for duplicate/bad blocks */
diff --git a/e2fsck/problem.h b/e2fsck/problem.h
index 3fabc90..f2bd414 100644
--- a/e2fsck/problem.h
+++ b/e2fsck/problem.h
@@ -550,6 +550,9 @@ struct problem_context {
/* Invalid bad inode */
#define PR_1_INVALID_BAD_INODE 0x010065
+/* Extent has zero length */
+#define PR_1_EXTENT_LENGTH_ZERO 0x010066
+
/*
* Pass 1b errors
*/
diff --git a/tests/f_ext_zero_len/expect.1 b/tests/f_ext_zero_len/expect.1
new file mode 100644
index 0000000..40109b3
--- /dev/null
+++ b/tests/f_ext_zero_len/expect.1
@@ -0,0 +1,13 @@
+Pass 1: Checking inodes, blocks, and sizes
+Inode 12 has zero length extent
+ (invalid logical block 0, physical block 37)
+Clear? yes
+
+Pass 2: Checking directory structure
+Pass 3: Checking directory connectivity
+Pass 4: Checking reference counts
+Pass 5: Checking group summary information
+
+test_filesys: ***** FILE SYSTEM WAS MODIFIED *****
+test_filesys: 12/16 files (0.0% non-contiguous), 21/100 blocks
+Exit status is 1
diff --git a/tests/f_ext_zero_len/expect.2 b/tests/f_ext_zero_len/expect.2
new file mode 100644
index 0000000..4ee5d96
--- /dev/null
+++ b/tests/f_ext_zero_len/expect.2
@@ -0,0 +1,7 @@
+Pass 1: Checking inodes, blocks, and sizes
+Pass 2: Checking directory structure
+Pass 3: Checking directory connectivity
+Pass 4: Checking reference counts
+Pass 5: Checking group summary information
+test_filesys: 12/16 files (0.0% non-contiguous), 21/100 blocks
+Exit status is 0
diff --git a/tests/f_ext_zero_len/image.gz b/tests/f_ext_zero_len/image.gz
new file mode 100644
index 0000000000000000000000000000000000000000..a03e5fd890f56538dfe97e02439c9d2132912fc6
GIT binary patch
literal 576
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z_m<uzE-#;UwdQD1!NL&s{|to%7tbzo`m6lMScF~ni0Z!6OQW*cE^1w@vHNgVbvpO^
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zzHh4g;<|1B<G<h2w#y#R^I}_b`qz)1g~tUnj`$ptd3m+oaLL|_J5Bw%`@ahO*}v=V
zrR(nx_{SzpS+Y0#fy&xrssC(zS6}@jRi`!O^0QY_zkfWv>X&V~KddfTLpA)`H7o69
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zi2)fL_%PFVx>WSf*>CsFUU}#AJNs!{cVF<|_U~NE!teD*6yNZA*67rG?Az@dx$Rwf
zUi37Jr!KF}A33j$_*3{t{qM)`ufM&%xA1$Fn)UzYXZuZLUYxg2Jn+X@F8EgKH~FI<
z%MJ9z%g)r_Pg`;DbNsU#{@V;UK7ZS0d{#kRzclKt-_ww_QM1?ig})Mirro{vRMO^{
VYvv3TfyFPlWo9n(W|+Xp001_Q4H*Cc
literal 0
Hc-jL100001
diff --git a/tests/f_ext_zero_len/name b/tests/f_ext_zero_len/name
new file mode 100644
index 0000000..ada4a72
--- /dev/null
+++ b/tests/f_ext_zero_len/name
@@ -0,0 +1 @@
+extent with zero length
--
1.7.9.107.g97f9a
--
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