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Cygwin: flock: Fix overlap handling in lf_setlock() and lf_clearlock() 

Currently, create_lock_obj() can create multiple locks with the same
lock range that have different version number. However, lf_setlock()
and lf_clearlock() cannot handle this case appropriately. With this
patch, make lf_setlock() and lf_clearlock() find overlap again even
when ovcase = 1 (lock and overlap have the same lock range).

Addresses: https://cygwin.com/pipermail/cygwin/2024-November/256750.html
Fixes: 2e560a092c ("* flock.cc (LOCK_OBJ_NAME_LEN): Change to accommodate extra lf_ver field.")
Reported-by: Sebastian Feld <sebastian.n.feld@gmail.com>
Reviewed-by: Corinna Vinschen <corinna@vinschen.de>
Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>
This commit is contained in:
Takashi Yano 2024-11-15 21:58:22 +09:00
parent e7ef920d7d
commit 8dee07a1f1
2 changed files with 21 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
winsup/cygwin/flock.cc
View File

@ -1410,12 +1410,16 @@ lf_setlock (lockf_t *lock, inode_t *node, lockf_t **clean, HANDLE fhdl)
*/
if (lock_cnt > MAX_LOCKF_CNT - room_for_clearlock)
return ENOLCK;
/* Do not create a lock here. It should be done after all
overlaps have been removed. */
lf_wakelock (overlap, fhdl);
overlap->lf_type = lock->lf_type;
overlap->create_lock_obj ();
lock->lf_next = *clean;
*clean = lock;
break;
*prev = overlap->lf_next;
overlap->lf_next = *clean;
*clean = overlap;
/* We may have multiple versions (lf_ver) having same lock range.
Therefore, we need to find overlap repeatedly. (originally,
just 'break' here. */
continue;
case 2: /* overlap contains lock */
/*
@ -1563,10 +1567,16 @@ lf_clearlock (lockf_t *unlock, lockf_t **clean, HANDLE fhdl)
switch (ovcase)
{
case 1: /* overlap == lock */
case 3: /* lock contains overlap */
*prev = overlap->lf_next;
lf = overlap->lf_next;
overlap->lf_next = *clean;
*clean = overlap;
break;
first_loop = false;
/* We may have multiple versions (lf_ver) having same lock range.
Therefore, we need to find overlap repeatedly. (originally,
just 'break' here. */
continue;
case 2: /* overlap contains lock: split it */
if (overlap->lf_start == unlock->lf_start)
@ -1582,13 +1592,8 @@ lf_clearlock (lockf_t *unlock, lockf_t **clean, HANDLE fhdl)
overlap->lf_next->create_lock_obj ();
break;
case 3: /* lock contains overlap */
*prev = overlap->lf_next;
lf = overlap->lf_next;
overlap->lf_next = *clean;
*clean = overlap;
first_loop = false;
continue;
/* case 3: */ /* lock contains overlap */
/* Merged into case 1 */
case 4: /* overlap starts before lock */
overlap->lf_end = unlock->lf_start - 1;

3
winsup/cygwin/release/3.5.5
View File

@ -39,3 +39,6 @@ Fixes:
- Fix access violation in lf_clearlock() called from flock().
Addresses: https://cygwin.com/pipermail/cygwin/2024-November/256750.html
- Fix NtCreateEvent() error in create_lock_ob() called from flock().
Addresses: https://cygwin.com/pipermail/cygwin/2024-November/256750.html