| Message ID | 1370253616-8173-3-git-send-email-ruslan.bilovol@ti.com |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Jun 03, 2013 at 01:00:16PM +0300, Ruslan Bilovol wrote: > Added checks for NULL before dereferencing some pointers > > + if (!de || !bh || !dir) > + return 1; Do you know which one of these pointers was NULL? I want't make sure we're fixing the root issue as opposed to papering over it. I'm not seeing how any of these pointers could have been NULL (at least in my upstream kernel), and while I believe that this helped for your kernel, I want to make sure we understand exactly what was going on. Thanks, - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Ted, On Mon, Jun 3, 2013 at 6:40 PM, Theodore Ts'o <tytso@mit.edu> wrote: > On Mon, Jun 03, 2013 at 01:00:16PM +0300, Ruslan Bilovol wrote: >> Added checks for NULL before dereferencing some pointers >> >> + if (!de || !bh || !dir) >> + return 1; > > Do you know which one of these pointers was NULL? In my particular case, the ''de" pointer is NULL Regards, Ruslan > > I want't make sure we're fixing the root issue as opposed to papering > over it. I'm not seeing how any of these pointers could have been > NULL (at least in my upstream kernel), and while I believe that this > helped for your kernel, I want to make sure we understand exactly what > was going on. > > Thanks, > > - Ted > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c index f8d56e4..cf0875b 100644 --- a/fs/ext4/dir.c +++ b/fs/ext4/dir.c @@ -68,8 +68,12 @@ int __ext4_check_dir_entry(const char *function, unsigned int line, unsigned int offset) { const char *error_msg = NULL; - const int rlen = ext4_rec_len_from_disk(de->rec_len, - dir->i_sb->s_blocksize); + int rlen; + + if (!de || !bh || !dir) + return 1; + + rlen = ext4_rec_len_from_disk(de->rec_len, dir->i_sb->s_blocksize); if (unlikely(rlen < EXT4_DIR_REC_LEN(1))) error_msg = "rec_len is smaller than minimal";
Added checks for NULL before dereferencing some pointers This fixes next issue: [ 1531.530609] Unable to handle kernel NULL pointer dereference at virtual address 00000004 [ 1531.543151] pgd = d6068000 [ 1531.546112] [00000004] *pgd=00000000 [ 1531.550109] Internal error: Oops: 5 [#1] PREEMPT SMP ARM [ 1531.555816] Modules linked in: rproc_drm(O) tf_driver(O) gps_drv wl18xx(O) wl12xx(O) wlcore(O) mac80211(O) cfg80211(O) pvrsrvkm_sgx540_120(O) compat(O) [ 1531.571105] CPU: 0 Tainted: G W O (3.4.34 #1) [ 1531.576934] PC is at __ext4_check_dir_entry+0x24/0x1a4 [ 1531.582550] LR is at ext4_readdir+0x270/0x7fc [ 1531.587249] pc : [<c017a788>] lr : [<c017ab78>] psr: 80000113 [ 1531.587249] sp : d6051e50 ip : 00000000 fp : d6051eb4 [ 1531.599700] r10: d4f0fdb0 r9 : c06a5c54 r8 : 000000d5 [ 1531.605377] r7 : d4c54540 r6 : d4634948 r5 : 00000000 r4 : 00000000 [ 1531.612396] r3 : d4634948 r2 : d4f0fdb0 r1 : 000000d5 r0 : c06a5c54 [ 1531.619476] Flags: Nzcv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user [ 1531.627166] Control: 10c5387d Table: 9606804a DAC: 00000015 [...] [ 1532.654876] Backtrace: [ 1532.657653] [<c017a764>] (__ext4_check_dir_entry+0x0/0x1a4) from [<c017ab78>] (ext4_readdir+0x270/0x7fc) [ 1532.667968] [<c017a908>] (ext4_readdir+0x0/0x7fc) from [<c0124860>] (vfs_readdir+0x9c/0xc0) [ 1532.677062] [<c01247c4>] (vfs_readdir+0x0/0xc0) from [<c0124a0c>] (sys_getdents64+0x68/0xc0) [ 1532.686248] [<c01249a4>] (sys_getdents64+0x0/0xc0) from [<c0013680>] (ret_fast_syscall+0x0/0x30) [ 1532.695800] r7:000000d9 r6:00000000 r5:416d4168 r4:416d4158 [ 1532.702270] Code: e1a07003 e1a09000 e1a08001 e59b3008 (e1dc40b4) Signed-off-by: Ruslan Bilovol <ruslan.bilovol@ti.com> --- fs/ext4/dir.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)